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Linux Distros Unpatched Vulnerability : CVE-2026-56865

🗓️ 14 Aug 2026 00:00:00Reported by TenableType 
nessus
 nessus
🔗 www.tenable.com👁 3 Views

Malicious GOPROXY can forge sumdb tiles to bypass GOSUMDB checks and inject attacker content into local Go module cache.

Related
Refs
Code
ReporterTitlePublishedViews
Family
attackerkb
ATTACKERKB
CVE-2026-56865
13 Aug 202621:58
attackerkb
cgr
Chainguard
CVE-2026-56865 vulnerabilities
14 Aug 202620:25
cgr
cve
CVE
CVE-2026-56865
13 Aug 202621:58
cve
cvelist
Cvelist
CVE-2026-56865 Fix transparency log tile verification bypass in golang.org/x/mod/sumdb/tlog
13 Aug 202621:58
cvelist
debiancve
Debian CVE
CVE-2026-56865
13 Aug 202621:58
debiancve
euvd
EUVD
EUVD-2026-58513
13 Aug 202621:58
euvd
nvd
NVD
CVE-2026-56865
13 Aug 202622:17
nvd
osv
OSV
CGA-JW38-QQ2G-45FW
14 Aug 202608:12
osv
osv
OSV
DEBIAN-CVE-2026-56865
13 Aug 202622:17
osv
osv
OSV
GO-2026-6179 Fix transparency log tile verification bypass in golang.org/x/mod/sumdb/tlog
13 Aug 202621:43
osv
Rows per page
#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(335371);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/08/14");

  script_cve_id("CVE-2026-56865");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-56865");

  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.

  - A malicious GOPROXY was previously capable of forging up to two sumdb tiles that allow for a requested
    module to bypass the GOSUMDB check and persist attacker-controlled module content to a local Go module
    cache. This attack allows for a malicious GOPROXY to serve malicious module content that cannot be
    detected by evaluating the transparency log. All tiles are now correctly verified against their parents.
    In order to determine if you have been affected: rm -r go.sum go.work.sum vendor/ && go mod tidy
    (CVE-2026-56865)

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-2026-56865");
  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:L/AC:H/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:L/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:U/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-56865");

  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:"2026/08/13");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/08/14");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:11.0");
  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:debian:debian_linux:golang-1.15");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:golang-1.19");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:golang-1.24");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:golang-1.25");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:golang-1.26");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:golang-1.27");
  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-11", "Host/OS/Debian Linux-12", "Host/OS/Debian Linux-13", "Host/OS/Debian Linux-14");

  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-11": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "11",
        "pkgs": [
          {"reference": "golang-1.15"},
          {"reference": "golang-1.15-doc"},
          {"reference": "golang-1.15-go"},
          {"reference": "golang-1.15-src"}
        ]
      }
    ]
  },
  "Debian Linux-12": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "12",
        "pkgs": [
          {"reference": "golang-1.19"},
          {"reference": "golang-1.19-doc"},
          {"reference": "golang-1.19-go"},
          {"reference": "golang-1.19-src"}
        ]
      }
    ]
  },
  "Debian Linux-13": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "13",
        "pkgs": [
          {"reference": "golang-1.24"},
          {"reference": "golang-1.24-doc"},
          {"reference": "golang-1.24-go"},
          {"reference": "golang-1.24-src"}
        ]
      }
    ]
  },
  "Debian Linux-14": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "14",
        "pkgs": [
          {"reference": "golang-1.25"},
          {"reference": "golang-1.25-doc"},
          {"reference": "golang-1.25-go"},
          {"reference": "golang-1.25-src"},
          {"reference": "golang-1.26"},
          {"reference": "golang-1.26-doc"},
          {"reference": "golang-1.26-go"},
          {"reference": "golang-1.26-src"},
          {"reference": "golang-1.27"},
          {"reference": "golang-1.27-doc"},
          {"reference": "golang-1.27-go"},
          {"reference": "golang-1.27-src"}
        ]
      }
    ]
  }
};

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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14 Aug 2026 00:00Current
5.4Medium risk
Vulners AI Score5.4
CVSS 3.18.4
EPSS0.00123
SSVC
3