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Linux Distros Unpatched Vulnerability : CVE-2026-52844

🗓️ 24 Jun 2026 00:00:00Reported by TenableType 
nessus
 nessus
🔗 www.tenable.com👁 5 Views

Linux host has unpatched Caddy flaw enabling unauthenticated remote bypass of private paths on Windows before 2.11.4.

Related
Refs
Code
ReporterTitlePublishedViews
Family
FreeBSD
caddy -- multiple vulnerabilities
8 Jun 202600:00
freebsd
ATTACKERKB
CVE-2026-52844
23 Jun 202617:50
attackerkb
Circl
CVE-2026-52844
8 Jun 202622:24
circl
CVE
CVE-2026-52844
23 Jun 202617:50
cve
Cvelist
CVE-2026-52844 Caddy: Windows `file_server` path authorization bypass via encoded backslash
23 Jun 202617:50
cvelist
Debian CVE
CVE-2026-52844
23 Jun 202617:50
debiancve
EUVD
EUVD-2026-38557
23 Jun 202617:50
euvd
Tenable Nessus
FreeBSD : caddy -- multiple vulnerabilities (94f93681-6775-11f1-8044-002590af0794)
14 Jun 202600:00
nessus
Github Security Blog
Caddy: Windows `file_server` path authorization bypass via encoded backslash
16 Jun 202621:28
github
NVD
CVE-2026-52844
23 Jun 202618:18
nvd
Rows per page
#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(322429);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/06/24");

  script_cve_id("CVE-2026-52844");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-52844");

  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.

  - Caddy is an extensible server platform that uses TLS by default. Prior to 2.11.4, on Windows, Caddy path
    matchers treat /private\secret.txt as outside /private/*, but file_server later resolves the same request
    path as private\secret.txt on disk. An unauthenticated remote client can bypass Caddy path-scoped
    auth/deny routes protecting /private/*. This vulnerability is fixed in 2.11.4. (CVE-2026-52844)

Note that Nessus relies on the presence of the package as reported by the vendor.");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-52844");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2026-52844");
  script_set_attribute(attribute:"solution", value:
"There is no known solution at this time.");
  script_set_attribute(attribute:"agent", value:"unix");
  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:"cvss3_score_source", value:"CVE-2026-52844");

  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:"2026/06/13");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/06/24");

  script_set_attribute(attribute:"plugin_type", value:"local");
  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:25.10");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:26.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:12.0");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:13.0");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:14.0");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:caddy");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:caddy");
  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/Debian Linux-12", "Host/OS/Debian Linux-13", "Host/OS/Debian Linux-14", "Host/OS/Ubuntu Linux-24.04", "Host/OS/Ubuntu Linux-25.10", "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 = {
  "Debian Linux-12": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "12",
        "pkgs": [
          {"reference": "caddy"}
        ]
      }
    ]
  },
  "Debian Linux-13": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "13",
        "pkgs": [
          {"reference": "caddy"}
        ]
      }
    ]
  },
  "Debian Linux-14": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "14",
        "pkgs": [
          {"reference": "caddy"}
        ]
      }
    ]
  },
  "Ubuntu Linux-24.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "24.04",
        "pkgs": [
          {"reference": "caddy"}
        ]
      }
    ]
  },
  "Ubuntu Linux-25.10": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "25.10",
        "pkgs": [
          {"reference": "caddy"}
        ]
      }
    ]
  },
  "Ubuntu Linux-26.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "26.04",
        "pkgs": [
          {"reference": "caddy"}
        ]
      }
    ]
  }
};

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 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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24 Jun 2026 00:00Current
6Medium risk
Vulners AI Score6
CVSS 3.17.5
EPSS0.00409
SSVC
5