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Linux Distros Unpatched Vulnerability : CVE-2026-66835

🗓️ 03 Sep 2026 00:00:00Reported by TenableType 
nessus
 nessus🔗 www.tenable.com👁 5 Views

Path Equivalence in Erlang/OTP inets httpd allows unauthenticated file read bypassing mod_auth.

Related
Refs
Code
ReporterTitlePublishedViews
Family
circl
Circl		CVE-2026-66835
2 Sep 202612:45
–circl
cve
CVE		CVE-2026-66835
1 Sep 202614:49
–cve
cvelist
Cvelist		CVE-2026-66835 httpd mod_auth directory protection bypassed by a doubled slash in the request path
1 Sep 202614:49
–cvelist
debiancve
Debian CVE		CVE-2026-66835
1 Sep 202614:49
–debiancve
freebsd
FreeBSD		Erlang/OTP -- multiple vulnerabilities in inets, stdlib, snmp and eldap
1 Sep 202600:00
–freebsd
euvd
EUVD		EUVD-2026-69245
1 Sep 202614:49
–euvd
nessus
Tenable Nessus		FreeBSD : Erlang/OTP -- multiple vulnerabilities in inets, stdlib, snmp and eldap (e9dfc357-a63f-11f1-9195-4c526214c986)
3 Sep 202600:00
–nessus
mscve
Microsoft CVE		httpd mod_auth directory protection bypassed by a doubled slash in the request path
3 Sep 202608:04
–mscve
nvd
NVD		CVE-2026-66835
1 Sep 202615:17
–nvd
osv
OSV		AZL-98463 CVE-2026-66835 affecting package erlang 26.2.5.21-4
1 Sep 202615:17
–osv
Rows per page
#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(342478);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/03");

  script_cve_id("CVE-2026-66835");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-66835");

  script_set_attribute(attribute:"synopsis", value:
"The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be
patched.");
  script_set_attribute(attribute:"description", value:
"The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied
patch available.

  - Path Equivalence vulnerability in Erlang/OTP inets httpd allows a remote unauthenticated attacker to read
    files inside a mod_auth protected directory by prefixing the request path with an extra slash.
    httpd_request:validate_uri/1 normalises the request URI with uri_string:normalize/1, which performs RFC
    3986 dot-segment removal but does not collapse empty path segments, so a doubled slash survives.
    mod_alias:real_name/3 concatenates the document root with that URI, and mod_auth:secret_path/3 then
    decides whether the result lies inside a protected directory block by running the configured directory
    path as an unanchored regular expression against it. The doubled slash breaks the contiguous substring the
    regex needs, so the request is treated as unprotected and no authentication challenge is issued, while
    mod_get opens the same path and the operating system collapses the doubled slash and returns the protected
    file. The same path mismatch also evades the per-path accounting in mod_security. This issue affects OTP
    from OTP 17.0 before OTP 27.3.4.17, from OTP 28.0 before OTP 28.5.0.6, and from OTP 29.0 before OTP
    29.0.6, corresponding to inets from 5.10 before 9.3.2.7, from 9.4 before 9.6.2.3, and from 9.7 before
    9.7.2. Whether OTP before OTP 17.0, corresponding to inets before 5.10, is affected is unknown.
    (CVE-2026-66835)

Note that Nessus relies on the presence of the package as reported by the vendor.");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2026-66835");
  script_set_attribute(attribute:"solution", value:
"There is no known solution at this time.");
  script_set_attribute(attribute:"agent", value:"unix");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:N");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:U/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:U/RC:C");
  script_set_attribute(attribute:"cvss4_vector", value:"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N");
  script_set_attribute(attribute:"cvss4_threat_vector", value:"CVSS:4.0/E:U");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-66835");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");
  script_set_attribute(attribute:"vendor_unpatched", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/09/01");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/03");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:14.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:16.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:18.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:20.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:22.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:24.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:26.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:erlang");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Misc.");

  script_copyright(english:"This script is Copyright (C) 2026 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info2.nasl", "set_linux_os_id.nasl");
  script_require_keys("Host/cpu", "Host/local_checks_enabled", "global_settings/vendor_unpatched", "Host/OS/identifier");
  script_require_ports("Host/OS/Ubuntu Linux-14.04", "Host/OS/Ubuntu Linux-16.04", "Host/OS/Ubuntu Linux-18.04", "Host/OS/Ubuntu Linux-20.04", "Host/OS/Ubuntu Linux-22.04", "Host/OS/Ubuntu Linux-24.04", "Host/OS/Ubuntu Linux-26.04");

  exit(0);
}

if (!get_kb_item("global_settings/vendor_unpatched")) exit(0, "Unpatched Vulnerabilities Detection not active.");
if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
if (empty_or_null(get_one_kb_item("Host/Debian/dpkg-l"))) audit(AUDIT_PACKAGE_LIST_MISSING);

include('linux_unpatched.inc');

var distro_constraints_array = {
  "Ubuntu Linux-14.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "14.04",
        "pkgs": [
          {"reference": "erlang"},
          {"reference": "erlang-appmon"},
          {"reference": "erlang-asn1"},
          {"reference": "erlang-base"},
          {"reference": "erlang-base-hipe"},
          {"reference": "erlang-common-test"},
          {"reference": "erlang-corba"},
          {"reference": "erlang-crypto"},
          {"reference": "erlang-dbg"},
          {"reference": "erlang-debugger"},
          {"reference": "erlang-dev"},
          {"reference": "erlang-dialyzer"},
          {"reference": "erlang-diameter"},
          {"reference": "erlang-doc"},
          {"reference": "erlang-edoc"},
          {"reference": "erlang-eldap"},
          {"reference": "erlang-erl-docgen"},
          {"reference": "erlang-et"},
          {"reference": "erlang-eunit"},
          {"reference": "erlang-examples"},
          {"reference": "erlang-gs"},
          {"reference": "erlang-ic"},
          {"reference": "erlang-ic-java"},
          {"reference": "erlang-inets"},
          {"reference": "erlang-jinterface"},
          {"reference": "erlang-manpages"},
          {"reference": "erlang-megaco"},
          {"reference": "erlang-mnesia"},
          {"reference": "erlang-mode"},
          {"reference": "erlang-nox"},
          {"reference": "erlang-observer"},
          {"reference": "erlang-odbc"},
          {"reference": "erlang-os-mon"},
          {"reference": "erlang-parsetools"},
          {"reference": "erlang-percept"},
          {"reference": "erlang-pman"},
          {"reference": "erlang-public-key"},
          {"reference": "erlang-reltool"},
          {"reference": "erlang-runtime-tools"},
          {"reference": "erlang-snmp"},
          {"reference": "erlang-src"},
          {"reference": "erlang-ssh"},
          {"reference": "erlang-ssl"},
          {"reference": "erlang-syntax-tools"},
          {"reference": "erlang-test-server"},
          {"reference": "erlang-toolbar"},
          {"reference": "erlang-tools"},
          {"reference": "erlang-tv"},
          {"reference": "erlang-typer"},
          {"reference": "erlang-webtool"},
          {"reference": "erlang-x11"},
          {"reference": "erlang-xmerl"}
        ]
      }
    ]
  },
  "Ubuntu Linux-16.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "16.04",
        "pkgs": [
          {"reference": "erlang"},
          {"reference": "erlang-asn1"},
          {"reference": "erlang-base"},
          {"reference": "erlang-base-hipe"},
          {"reference": "erlang-common-test"},
          {"reference": "erlang-corba"},
          {"reference": "erlang-crypto"},
          {"reference": "erlang-dbg"},
          {"reference": "erlang-debugger"},
          {"reference": "erlang-dev"},
          {"reference": "erlang-dialyzer"},
          {"reference": "erlang-diameter"},
          {"reference": "erlang-doc"},
          {"reference": "erlang-edoc"},
          {"reference": "erlang-eldap"},
          {"reference": "erlang-erl-docgen"},
          {"reference": "erlang-et"},
          {"reference": "erlang-eunit"},
          {"reference": "erlang-examples"},
          {"reference": "erlang-gs"},
          {"reference": "erlang-ic"},
          {"reference": "erlang-ic-java"},
          {"reference": "erlang-inets"},
          {"reference": "erlang-jinterface"},
          {"reference": "erlang-manpages"},
          {"reference": "erlang-megaco"},
          {"reference": "erlang-mnesia"},
          {"reference": "erlang-mode"},
          {"reference": "erlang-nox"},
          {"reference": "erlang-observer"},
          {"reference": "erlang-odbc"},
          {"reference": "erlang-os-mon"},
          {"reference": "erlang-parsetools"},
          {"reference": "erlang-percept"},
          {"reference": "erlang-public-key"},
          {"reference": "erlang-reltool"},
          {"reference": "erlang-runtime-tools"},
          {"reference": "erlang-snmp"},
          {"reference": "erlang-src"},
          {"reference": "erlang-ssh"},
          {"reference": "erlang-ssl"},
          {"reference": "erlang-syntax-tools"},
          {"reference": "erlang-test-server"},
          {"reference": "erlang-tools"},
          {"reference": "erlang-typer"},
          {"reference": "erlang-webtool"},
          {"reference": "erlang-wx"},
          {"reference": "erlang-x11"},
          {"reference": "erlang-xmerl"}
        ]
      }
    ]
  },
  "Ubuntu Linux-18.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "18.04",
        "pkgs": [
          {"reference": "erlang"},
          {"reference": "erlang-asn1"},
          {"reference": "erlang-base"},
          {"reference": "erlang-base-hipe"},
          {"reference": "erlang-common-test"},
          {"reference": "erlang-corba"},
          {"reference": "erlang-crypto"},
          {"reference": "erlang-debugger"},
          {"reference": "erlang-dev"},
          {"reference": "erlang-dialyzer"},
          {"reference": "erlang-diameter"},
          {"reference": "erlang-doc"},
          {"reference": "erlang-edoc"},
          {"reference": "erlang-eldap"},
          {"reference": "erlang-erl-docgen"},
          {"reference": "erlang-et"},
          {"reference": "erlang-eunit"},
          {"reference": "erlang-examples"},
          {"reference": "erlang-ic"},
          {"reference": "erlang-ic-java"},
          {"reference": "erlang-inets"},
          {"reference": "erlang-jinterface"},
          {"reference": "erlang-manpages"},
          {"reference": "erlang-megaco"},
          {"reference": "erlang-mnesia"},
          {"reference": "erlang-mode"},
          {"reference": "erlang-nox"},
          {"reference": "erlang-observer"},
          {"reference": "erlang-odbc"},
          {"reference": "erlang-os-mon"},
          {"reference": "erlang-parsetools"},
          {"reference": "erlang-public-key"},
          {"reference": "erlang-reltool"},
          {"reference": "erlang-runtime-tools"},
          {"reference": "erlang-snmp"},
          {"reference": "erlang-src"},
          {"reference": "erlang-ssh"},
          {"reference": "erlang-ssl"},
          {"reference": "erlang-syntax-tools"},
          {"reference": "erlang-tools"},
          {"reference": "erlang-wx"},
          {"reference": "erlang-x11"},
          {"reference": "erlang-xmerl"}
        ]
      }
    ]
  },
  "Ubuntu Linux-20.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "20.04",
        "pkgs": [
          {"reference": "erlang"},
          {"reference": "erlang-asn1"},
          {"reference": "erlang-base"},
          {"reference": "erlang-base-hipe"},
          {"reference": "erlang-common-test"},
          {"reference": "erlang-crypto"},
          {"reference": "erlang-debugger"},
          {"reference": "erlang-dev"},
          {"reference": "erlang-dialyzer"},
          {"reference": "erlang-diameter"},
          {"reference": "erlang-doc"},
          {"reference": "erlang-edoc"},
          {"reference": "erlang-eldap"},
          {"reference": "erlang-erl-docgen"},
          {"reference": "erlang-et"},
          {"reference": "erlang-eunit"},
          {"reference": "erlang-examples"},
          {"reference": "erlang-ftp"},
          {"reference": "erlang-inets"},
          {"reference": "erlang-jinterface"},
          {"reference": "erlang-manpages"},
          {"reference": "erlang-megaco"},
          {"reference": "erlang-mnesia"},
          {"reference": "erlang-mode"},
          {"reference": "erlang-nox"},
          {"reference": "erlang-observer"},
          {"reference": "erlang-odbc"},
          {"reference": "erlang-os-mon"},
          {"reference": "erlang-parsetools"},
          {"reference": "erlang-public-key"},
          {"reference": "erlang-reltool"},
          {"reference": "erlang-runtime-tools"},
          {"reference": "erlang-snmp"},
          {"reference": "erlang-src"},
          {"reference": "erlang-ssh"},
          {"reference": "erlang-ssl"},
          {"reference": "erlang-syntax-tools"},
          {"reference": "erlang-tftp"},
          {"reference": "erlang-tools"},
          {"reference": "erlang-wx"},
          {"reference": "erlang-x11"},
          {"reference": "erlang-xmerl"}
        ]
      }
    ]
  },
  "Ubuntu Linux-22.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "22.04",
        "pkgs": [
          {"reference": "erlang"},
          {"reference": "erlang-asn1"},
          {"reference": "erlang-base"},
          {"reference": "erlang-common-test"},
          {"reference": "erlang-crypto"},
          {"reference": "erlang-debugger"},
          {"reference": "erlang-dev"},
          {"reference": "erlang-dialyzer"},
          {"reference": "erlang-diameter"},
          {"reference": "erlang-doc"},
          {"reference": "erlang-edoc"},
          {"reference": "erlang-eldap"},
          {"reference": "erlang-erl-docgen"},
          {"reference": "erlang-et"},
          {"reference": "erlang-eunit"},
          {"reference": "erlang-examples"},
          {"reference": "erlang-ftp"},
          {"reference": "erlang-inets"},
          {"reference": "erlang-jinterface"},
          {"reference": "erlang-manpages"},
          {"reference": "erlang-megaco"},
          {"reference": "erlang-mnesia"},
          {"reference": "erlang-mode"},
          {"reference": "erlang-nox"},
          {"reference": "erlang-observer"},
          {"reference": "erlang-odbc"},
          {"reference": "erlang-os-mon"},
          {"reference": "erlang-parsetools"},
          {"reference": "erlang-public-key"},
          {"reference": "erlang-reltool"},
          {"reference": "erlang-runtime-tools"},
          {"reference": "erlang-snmp"},
          {"reference": "erlang-src"},
          {"reference": "erlang-ssh"},
          {"reference": "erlang-ssl"},
          {"reference": "erlang-syntax-tools"},
          {"reference": "erlang-tftp"},
          {"reference": "erlang-tools"},
          {"reference": "erlang-wx"},
          {"reference": "erlang-x11"},
          {"reference": "erlang-xmerl"}
        ]
      }
    ]
  },
  "Ubuntu Linux-24.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "24.04",
        "pkgs": [
          {"reference": "erlang"},
          {"reference": "erlang-asn1"},
          {"reference": "erlang-base"},
          {"reference": "erlang-common-test"},
          {"reference": "erlang-crypto"},
          {"reference": "erlang-debugger"},
          {"reference": "erlang-dev"},
          {"reference": "erlang-dialyzer"},
          {"reference": "erlang-diameter"},
          {"reference": "erlang-doc"},
          {"reference": "erlang-edoc"},
          {"reference": "erlang-eldap"},
          {"reference": "erlang-erl-docgen"},
          {"reference": "erlang-et"},
          {"reference": "erlang-eunit"},
          {"reference": "erlang-examples"},
          {"reference": "erlang-ftp"},
          {"reference": "erlang-inets"},
          {"reference": "erlang-jinterface"},
          {"reference": "erlang-manpages"},
          {"reference": "erlang-megaco"},
          {"reference": "erlang-mnesia"},
          {"reference": "erlang-mode"},
          {"reference": "erlang-nox"},
          {"reference": "erlang-observer"},
          {"reference": "erlang-odbc"},
          {"reference": "erlang-os-mon"},
          {"reference": "erlang-parsetools"},
          {"reference": "erlang-public-key"},
          {"reference": "erlang-reltool"},
          {"reference": "erlang-runtime-tools"},
          {"reference": "erlang-snmp"},
          {"reference": "erlang-src"},
          {"reference": "erlang-ssh"},
          {"reference": "erlang-ssl"},
          {"reference": "erlang-syntax-tools"},
          {"reference": "erlang-tftp"},
          {"reference": "erlang-tools"},
          {"reference": "erlang-wx"},
          {"reference": "erlang-x11"},
          {"reference": "erlang-xmerl"}
        ]
      }
    ]
  },
  "Ubuntu Linux-26.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "26.04",
        "pkgs": [
          {"reference": "erlang"},
          {"reference": "erlang-asn1"},
          {"reference": "erlang-base"},
          {"reference": "erlang-common-test"},
          {"reference": "erlang-crypto"},
          {"reference": "erlang-debugger"},
          {"reference": "erlang-dev"},
          {"reference": "erlang-dialyzer"},
          {"reference": "erlang-diameter"},
          {"reference": "erlang-doc"},
          {"reference": "erlang-edoc"},
          {"reference": "erlang-eldap"},
          {"reference": "erlang-et"},
          {"reference": "erlang-eunit"},
          {"reference": "erlang-examples"},
          {"reference": "erlang-ftp"},
          {"reference": "erlang-inets"},
          {"reference": "erlang-jinterface"},
          {"reference": "erlang-megaco"},
          {"reference": "erlang-mnesia"},
          {"reference": "erlang-mode"},
          {"reference": "erlang-nox"},
          {"reference": "erlang-observer"},
          {"reference": "erlang-odbc"},
          {"reference": "erlang-os-mon"},
          {"reference": "erlang-parsetools"},
          {"reference": "erlang-public-key"},
          {"reference": "erlang-reltool"},
          {"reference": "erlang-runtime-tools"},
          {"reference": "erlang-snmp"},
          {"reference": "erlang-src"},
          {"reference": "erlang-ssh"},
          {"reference": "erlang-ssl"},
          {"reference": "erlang-syntax-tools"},
          {"reference": "erlang-tftp"},
          {"reference": "erlang-tools"},
          {"reference": "erlang-wx"},
          {"reference": "erlang-x11"},
          {"reference": "erlang-xmerl"}
        ]
      }
    ]
  }
};

var distro_constraints_values = linux_unpatched::get_distro_constraints(distro_constraints_arr:distro_constraints_array);
if (empty_or_null(distro_constraints_values)) audit(AUDIT_HOST_NOT, 'affected');

var third_party_support = get_kb_item('Host/OS/extended-third-party');
if (!empty_or_null(third_party_support)) {
    var third_party_vendors = distro_constraints_values['third_party'];
    if (!empty_or_null(third_party_vendors)) {
        var vendor;
        foreach vendor (third_party_vendors) {
            if (vendor == third_party_support) exit(0, 'A third party management patch is available for this vulnerability from ' + vendor + '.\n');
        }
    }
}

var report = linux_unpatched::check_unpatched_constraints(distro_constraints_values:distro_constraints_values);

if (!empty_or_null(report))
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_WARNING,
      extra      : report
  );
  exit(0);
}
else
{
  audit(AUDIT_HOST_NOT, 'affected');
}

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03 Sep 2026 00:00Current
CVSS 48.2
EPSS0.00635
SSVC
Erlang/OTP inetsPath Equivalencemod_auth bypasshttpdUnauthenticatedFile Read
5