Amazon Linux 2023 : python3-dulwich (ALAS2023-2026-2026)

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

include('compat.inc');

if (description)
{
  script_id(332007);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/08/04");

  script_cve_id("CVE-2026-38974", "CVE-2026-42305", "CVE-2026-47734");

  script_name(english:"Amazon Linux 2023 : python3-dulwich (ALAS2023-2026-2026)");

  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 ALAS2023-2026-2026 advisory.

    Dulwich through 1.1.0 was found to be missing SSH host key verification in contrib/paramiko_vendor.py.
    (CVE-2026-38974)

    Arbitrary file write leading to remote code execution when cloning or checking out a malicious Git
    repository on Windows.

    Dulwich's path-element validator accepted tree entries whose filenames contained bytes that Windows
    interprets as structural path syntax:

    \ -- the Windows path separator. A single tree entry named .git\hooks\pre-commit.exe was treated as one
    valid filename on POSIX but materialized as nested directories .git/hooks/pre-commit.exe on Windows,
    planting a file inside the victim's .git directory. Git for Windows thenexecutes that hook on the next git
    commit, giving the attacker arbitrary code execution in the victim's user context. The same primitive can
    be used with ..\outside.txt to escape the work tree.: -- the NTFS alternate-data-stream marker.
    .git::$INDEX_ALLOCATION writes directly into the victim's .git entity, bypassing the .git-as-a-directory
    check.git~ -- NTFS 8.3 short-name aliases of .git. Only the literal git1 was rejected; git2, git10, GIT1,
    etc. were all accepted.Contributing configuration bugs made matters worse. The core.protectNTFS and
    core.protectHFS settings were looked up under a wrong option name and so user-set values were silently
    ignored, and core.protectNTFS only defaulted to true on Windows (Git upstream has defaulted it to true
    everywhere since CVE-2019-1353). Both have been corrected.

    Anyone who clones, fetches, or checks out an untrusted repository with Dulwich on Windows - either through
    the Dulwich CLI, porcelain.clone, or any downstream tool built on Dulwich - is impacted. POSIX clones are
    not directly exploitable (on POSIX \ is a literal filename byte), but a POSIX user can unknowingly
    propagate a malicious tree to Windows consumers via push or re-publication. (CVE-2026-42305)

    An uncontrolled-resource-consumption (memory exhaustion) denial-of-service vulnerability (CWE-400 /
    CWE-789).

    A client with push access could push a tiny crafted thin pack (~174 bytes) whose delta header declares a
    huge dest_size. When dulwich ingested it via add_thin_pack / apply_delta, it would allocate hundreds of MB
    of memory based on that attacker-controlled size, with no relationship to the actual bytes received.

    Who is impacted: Operators running a dulwich-based Git server that exposes git-receive-pack (i.e. accepts
    pushes) -for example via dulwich.server functionality, the HTTP smart server, or anything built on
    ReceivePackHandler. (CVE-2026-47734)

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/ALAS2023-2026-2026.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-2026-38974.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-42305.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-47734.html");
  script_set_attribute(attribute:"solution", value:
"Run 'dnf update python-dulwich --releasever 2023.12.20260803' or
  or 'dnf update --advisory ALAS2023-2026-2026 --releasever 2023.12.20260803' 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:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-42305");

  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:"2026/05/28");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/08/04");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/08/04");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:python-dulwich-debugsource");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:python-dulwich-doc");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:python3-dulwich");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:python3-dulwich-debuginfo");
  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':'python-dulwich-debugsource-0.20.18-1.amzn2023.0.3', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'python-dulwich-debugsource-0.20.18-1.amzn2023.0.3', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'python-dulwich-doc-0.20.18-1.amzn2023.0.3', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'python-dulwich-doc-0.20.18-1.amzn2023.0.3', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'python3-dulwich-0.20.18-1.amzn2023.0.3', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'python3-dulwich-0.20.18-1.amzn2023.0.3', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'python3-dulwich-debuginfo-0.20.18-1.amzn2023.0.3', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'python3-dulwich-debuginfo-0.20.18-1.amzn2023.0.3', '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, "python-dulwich-debugsource / python-dulwich-doc / python3-dulwich / etc");
}