Linux Distros Unpatched Vulnerability : CVE-2026-63729

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(329530);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/07/25");

  script_cve_id("CVE-2026-63729");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-63729");

  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.

  - The SyncTeX parser (synctex_parser.c) shipped with TeX Live and embedded by downstream consumers such as
    GNOME Evince contains a heap use-after-free vulnerability that allows attackers to crash applications or
    potentially execute arbitrary code by supplying a malformed .synctex or .synctex.gz file. A malformed
    SyncTeX file can construct a ref node with a NULL parent pointer, causing the replacement routine to fail
    to detach the node from its sibling chain, which triggers recursive freeing of live tree nodes and leaves
    dangling pointers that are later accessed by the parser during document load. (CVE-2026-63729)

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-2026-63729");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2026-63729");
  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:M/Au:N/C:P/I:P/A:P");
  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:N/UI:R/S:U/C:L/I:L/A:H");
  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:L/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:H/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-2026-63729");

  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:"2026/07/21");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/07/25");

  script_set_attribute(attribute:"plugin_type", value:"local");
  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:"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:"p-cpe:/a:canonical:ubuntu_linux:texlive-bin");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:texlive-bin");
  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/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 = {
  "Debian Linux-12": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "12",
        "pkgs": [
          {"reference": "libkpathsea-dev"},
          {"reference": "libkpathsea6"},
          {"reference": "libptexenc-dev"},
          {"reference": "libptexenc1"},
          {"reference": "libsynctex-dev"},
          {"reference": "libsynctex2"},
          {"reference": "libtexlua-dev"},
          {"reference": "libtexlua53"},
          {"reference": "libtexlua53-5"},
          {"reference": "libtexlua53-dev"},
          {"reference": "libtexluajit-dev"},
          {"reference": "libtexluajit2"},
          {"reference": "texlive-binaries"}
        ]
      }
    ]
  },
  "Debian Linux-11": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "11",
        "pkgs": [
          {"reference": "libkpathsea-dev"},
          {"reference": "libkpathsea6"},
          {"reference": "libptexenc-dev"},
          {"reference": "libptexenc1"},
          {"reference": "libsynctex-dev"},
          {"reference": "libsynctex2"},
          {"reference": "libtexlua53"},
          {"reference": "libtexlua53-dev"},
          {"reference": "libtexluajit-dev"},
          {"reference": "libtexluajit2"},
          {"reference": "texlive-binaries"}
        ]
      }
    ]
  },
  "Ubuntu Linux-20.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "20.04",
        "pkgs": [
          {"reference": "libkpathsea-dev"},
          {"reference": "libkpathsea6"},
          {"reference": "libptexenc-dev"},
          {"reference": "libptexenc1"},
          {"reference": "libsynctex-dev"},
          {"reference": "libsynctex2"},
          {"reference": "libtexlua53"},
          {"reference": "libtexlua53-dev"},
          {"reference": "libtexluajit-dev"},
          {"reference": "libtexluajit2"},
          {"reference": "texlive-binaries"}
        ]
      }
    ]
  },
  "Ubuntu Linux-22.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "22.04",
        "pkgs": [
          {"reference": "libkpathsea-dev"},
          {"reference": "libkpathsea6"},
          {"reference": "libptexenc-dev"},
          {"reference": "libptexenc1"},
          {"reference": "libsynctex-dev"},
          {"reference": "libsynctex2"},
          {"reference": "libtexlua53"},
          {"reference": "libtexlua53-dev"},
          {"reference": "libtexluajit-dev"},
          {"reference": "libtexluajit2"},
          {"reference": "texlive-binaries"}
        ]
      }
    ]
  },
  "Debian Linux-13": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "13",
        "pkgs": [
          {"reference": "libkpathsea-dev"},
          {"reference": "libkpathsea6"},
          {"reference": "libptexenc-dev"},
          {"reference": "libptexenc1"},
          {"reference": "libsynctex-dev"},
          {"reference": "libsynctex2"},
          {"reference": "libtexlua-dev"},
          {"reference": "libtexlua53"},
          {"reference": "libtexlua53-5"},
          {"reference": "libtexlua53-dev"},
          {"reference": "libtexluajit-dev"},
          {"reference": "libtexluajit2"},
          {"reference": "texlive-binaries"},
          {"reference": "texlive-binaries-sse2"}
        ]
      }
    ]
  },
  "Ubuntu Linux-24.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "24.04",
        "pkgs": [
          {"reference": "libkpathsea-dev"},
          {"reference": "libkpathsea6"},
          {"reference": "libptexenc-dev"},
          {"reference": "libptexenc1"},
          {"reference": "libsynctex-dev"},
          {"reference": "libsynctex2"},
          {"reference": "libtexlua-dev"},
          {"reference": "libtexlua53"},
          {"reference": "libtexlua53-5"},
          {"reference": "libtexlua53-dev"},
          {"reference": "libtexluajit-dev"},
          {"reference": "libtexluajit2"},
          {"reference": "texlive-binaries"},
          {"reference": "texlive-binaries-sse2"}
        ]
      }
    ]
  },
  "Ubuntu Linux-16.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "16.04",
        "pkgs": [
          {"reference": "libkpathsea-dev"},
          {"reference": "libkpathsea6"},
          {"reference": "libptexenc-dev"},
          {"reference": "libptexenc1"},
          {"reference": "libsynctex-dev"},
          {"reference": "libsynctex1"},
          {"reference": "libtexlua52"},
          {"reference": "libtexlua52-dev"},
          {"reference": "libtexluajit-dev"},
          {"reference": "libtexluajit2"},
          {"reference": "texlive-binaries"}
        ]
      }
    ]
  },
  "Ubuntu Linux-18.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "18.04",
        "pkgs": [
          {"reference": "libkpathsea-dev"},
          {"reference": "libkpathsea6"},
          {"reference": "libptexenc-dev"},
          {"reference": "libptexenc1"},
          {"reference": "libsynctex-dev"},
          {"reference": "libsynctex1"},
          {"reference": "libtexlua52"},
          {"reference": "libtexlua52-dev"},
          {"reference": "libtexluajit-dev"},
          {"reference": "libtexluajit2"},
          {"reference": "texlive-binaries"}
        ]
      }
    ]
  },
  "Ubuntu Linux-26.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "26.04",
        "pkgs": [
          {"reference": "texlive-bin"}
        ]
      }
    ]
  }
};

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');
}