Amazon Linux 2023 : libgit2, libgit2-devel (ALAS2023-2026-2083)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Amazon Linux 2023 Security Advisory ALAS2023-2026-2083.
##

include('compat.inc');

if (description)
{
  script_id(341845);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/08/31");

  script_cve_id(
    "CVE-2026-5917",
    "CVE-2026-53583",
    "CVE-2026-53584",
    "CVE-2026-53585",
    "CVE-2026-53586",
    "CVE-2026-53587"
  );

  script_name(english:"Amazon Linux 2023 : libgit2, libgit2-devel (ALAS2023-2026-2083)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Amazon Linux 2023 host is missing a security update.");
  script_set_attribute(attribute:"description", value:
"It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-2083 advisory.

    libgit2 Inverted IP SubjectAltName Comparison in OpenSSL Backend ( vuln_1_1_1 ) (CVE-2026-53583)

    libgit2 Submodule path traversal (CVE-2026-53584)

    Unbounded Memory Allocation via Delta Object Result-Size Header (CVE-2026-53585)

    libgit2's builtin HTTP transport follows offsite redirects for the initial smart HTTP request by default.
    If the redirected server then returns 401 Unauthorized, libgit2 asks the application credential callback
    for credentials using the original remote URL, not the redirected URL. The returned credential is then
    attached to the next request to the redirected host as an Authorization header. (CVE-2026-53586)

    libgit2 version 1.9.4 and below is vulnerable to a heap out-of-bounds read in set_data() in
    src/libgit2/transports/smart_pkt.c.

    The vulnerable code uses a fixed-size strncmp (smart_pkt.c:239) against the unvalidated capability buffer
    of a smart-protocol pkt-line. When the bytes following the pkt-line in the contiguous receive buffer
    happen to continue with ct-format=, the comparison spuriously matches, advancing format_str past the
    pkt-line boundary. The following memchr(format_str, ' ', len - (format_str - line)) (smart_pkt.c:246) then
    underflows its size_t size argument to ~SIZE_MAX and walks the heap looking for a space byte. An
    unauthenticated remote attacker who controls (or man-in-the-middles) a Git server reached over
    HTTP/HTTPS/SSH/git:// can trigger this on the FIRST ref-pkt of the refs advertisement, before any
    capability negotiation has taken place. The OOB walk causes a process crash (SIGSEGV) when memchr enters
    an unmapped page, and -- on heap layouts where memchr finds a stray space byte before crashing -- can
    additionally drive the git_error_set(...'%.*s', format_len, format_str) formatter to copy a large window
    of heap memory into the error string. (CVE-2026-53587)

    libgit2 versions v0.27.0 through v1.9.0 built with the libssh2 SSH backend (USE_SSH=libssh2) contain a
    shell command injection vulnerability that allows remote attackers to execute arbitrary commands on an SSH
    server by supplying a repository path containing unescaped shell metacharacters such as single quotes,
    semicolons, or pipes. The gen_proto() function in ssh_libssh2.c inserts the repository path directly into
    a shell command string without escaping special characters before passing it to libssh2_channel_exec(),
    enabling an attacker to craft a malicious submodule URL in a .gitmodules file that, when processed during
    a recursive clone, causes the remote server's shell to interpret injected commands under the victim's SSH
    user account. (CVE-2026-5917)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com//AL2023/ALAS2023-2026-2083.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/faqs.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-53583.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-53584.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-53585.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-53586.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-53587.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-5917.html");
  script_set_attribute(attribute:"solution", value:
"Run 'dnf update libgit2 --releasever 2023.12.20260831' or
  or 'dnf update --advisory ALAS2023-2026-2083 --releasever 2023.12.20260831' to update your system.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss4_vector", value:"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/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-2026-5917");
  script_set_attribute(attribute:"cvss3_score_source", value:"CVE-2026-53586");

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

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/07/23");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/08/31");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/08/31");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:libgit2");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:libgit2-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:libgit2-debugsource");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:libgit2-devel");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:amazon:linux:2023");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Amazon Linux Local Security Checks");

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

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/AmazonLinux/release", "Host/AmazonLinux/rpm-list");

  exit(0);
}

include("rpm2.inc");

if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);

var alas_release = get_kb_item("Host/AmazonLinux/release");
if (isnull(alas_release) || !strlen(alas_release)) audit(AUDIT_OS_NOT, "Amazon Linux");
var os_ver = pregmatch(pattern: "^AL(A|\d+|-\d+)", string:alas_release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, "Amazon Linux");
os_ver = os_ver[1];
if (os_ver != "-2023")
{
  if (os_ver == 'A') os_ver = 'AMI';
  audit(AUDIT_OS_NOT, "Amazon Linux 2023", "Amazon Linux " + os_ver);
}

if (!get_kb_item("Host/AmazonLinux/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING);

var pkgs = [
    {'reference':'libgit2-1.6.4-116.amzn2023', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libgit2-1.6.4-116.amzn2023', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libgit2-debuginfo-1.6.4-116.amzn2023', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libgit2-debuginfo-1.6.4-116.amzn2023', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libgit2-debugsource-1.6.4-116.amzn2023', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libgit2-debugsource-1.6.4-116.amzn2023', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libgit2-devel-1.6.4-116.amzn2023', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libgit2-devel-1.6.4-116.amzn2023', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE}
];

var flag = 0;
foreach var package_array ( pkgs ) {
  var reference = NULL;
  var _release = NULL;
  var sp = NULL;
  var _cpu = NULL;
  var el_string = NULL;
  var rpm_spec_vers_cmp = NULL;
  var epoch = NULL;
  var allowmaj = NULL;
  var exists_check = NULL;
  var cves = NULL;
  if (!empty_or_null(package_array['reference'])) reference = package_array['reference'];
  if (!empty_or_null(package_array['release'])) _release = package_array['release'];
  if (!empty_or_null(package_array['sp'])) sp = package_array['sp'];
  if (!empty_or_null(package_array['cpu'])) _cpu = package_array['cpu'];
  if (!empty_or_null(package_array['el_string'])) el_string = package_array['el_string'];
  if (!empty_or_null(package_array['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = package_array['rpm_spec_vers_cmp'];
  if (!empty_or_null(package_array['epoch'])) epoch = package_array['epoch'];
  if (!empty_or_null(package_array['allowmaj'])) allowmaj = package_array['allowmaj'];
  if (!empty_or_null(package_array['exists_check'])) exists_check = package_array['exists_check'];
  if (!empty_or_null(package_array['cves'])) cves = package_array['cves'];
  if (reference && _release && (!exists_check || rpm_exists(release:_release, rpm:exists_check))) {
    if (rpm_check(release:_release, sp:sp, cpu:_cpu, reference:reference, epoch:epoch, el_string:el_string, rpm_spec_vers_cmp:rpm_spec_vers_cmp, allowmaj:allowmaj, cves:cves)) flag++;
  }
}

if (flag)
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_HOLE,
      extra      : rpm_report_get()
  );
  exit(0);
}
else
{
  var tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "libgit2 / libgit2-debuginfo / libgit2-debugsource / etc");
}