Amazon Linux 2 : python3-urllib3, --advisory ALAS2-2026-3127 (ALAS-2026-3127)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Amazon Linux 2 Security Advisory ALAS-2026-3127.
##

include('compat.inc');

if (description)
{
  script_id(294890);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/01/21");

  script_cve_id("CVE-2024-37891", "CVE-2025-66418", "CVE-2025-66471");

  script_name(english:"Amazon Linux 2 : python3-urllib3, --advisory ALAS2-2026-3127 (ALAS-2026-3127)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Amazon Linux 2 host is missing a security update.");
  script_set_attribute(attribute:"description", value:
"The version of python3-urllib3 installed on the remote host is prior to 1.25.6-2. It is, therefore, affected by multiple
vulnerabilities as referenced in the ALAS2-2026-3127 advisory.

    urllib3 is a user-friendly HTTP client library for Python. When using urllib3's proxy support with
    `ProxyManager`, the `Proxy-Authorization` header is only sent to the configured proxy, as expected.
    However, when sending HTTP requests *without* using urllib3's proxy support, it's possible to accidentally
    configure the `Proxy-Authorization` header even though it won't have any effect as the request is not
    using a forwarding proxy or a tunneling proxy. In those cases, urllib3 doesn't treat the `Proxy-
    Authorization` HTTP header as one carrying authentication material and thus doesn't strip the header on
    cross-origin redirects. Because this is a highly unlikely scenario, we believe the severity of this
    vulnerability is low for almost all users. Out of an abundance of caution urllib3 will automatically strip
    the `Proxy-Authorization` header during cross-origin redirects to avoid the small chance that users are
    doing this on accident. Users should use urllib3's proxy support or disable automatic redirects to achieve
    safe processing of the `Proxy-Authorization` header, but we still decided to strip the header by default
    in order to further protect users who aren't using the correct approach. We believe the number of usages
    affected by this advisory is low. It requires all of the following to be true to be exploited: 1. Setting
    the `Proxy-Authorization` header without using urllib3's built-in proxy support. 2. Not disabling HTTP
    redirects. 3. Either not using an HTTPS origin server or for the proxy or target origin to redirect to a
    malicious origin. Users are advised to update to either version 1.26.19 or version 2.2.2. Users unable to
    upgrade may use the `Proxy-Authorization` header with urllib3's `ProxyManager`, disable HTTP redirects
    using `redirects=False` when sending requests, or not user the `Proxy-Authorization` header as
    mitigations. (CVE-2024-37891)

    urllib3 is a user-friendly HTTP client library for Python. Starting in version 1.24 and prior to 2.6.0,
    the number of links in the decompression chain was unbounded allowing a malicious server to insert a
    virtually unlimited number of compression steps leading to high CPU usage and massive memory allocation
    for the decompressed data. This vulnerability is fixed in 2.6.0. (CVE-2025-66418)

    urllib3 is a user-friendly HTTP client library for Python. Starting in version 1.0 and prior to 2.6.0, the
    Streaming API improperly handles highly compressed data. urllib3's streaming API is designed for the
    efficient handling of large HTTP responses by reading the content in chunks, rather than loading the
    entire response body into memory at once. When streaming a compressed response, urllib3 can perform
    decoding or decompression based on the HTTP Content-Encoding header (e.g., gzip, deflate, br, or zstd).
    The library must read compressed data from the network and decompress it until the requested chunk size is
    met. Any resulting decompressed data that exceeds the requested amount is held in an internal buffer for
    the next read operation. The decompression logic could cause urllib3 to fully decode a small amount of
    highly compressed data in a single operation. This can result in excessive resource consumption (high CPU
    usage and massive memory allocation for the decompressed data. (CVE-2025-66471)

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//AL2/ALAS2-2026-3127.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-2024-37891.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2025-66418.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2025-66471.html");
  script_set_attribute(attribute:"solution", value:
"Run 'yum update python3-urllib3' or
  or 'yum update --advisory ALAS2-2026-3127' to update your system.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:S/C:C/I:N/A:N");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss4_vector", value:"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H");
  script_set_attribute(attribute:"cvss4_threat_vector", value:"CVSS:4.0/E:P");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2024-37891");
  script_set_attribute(attribute:"cvss4_score_source", value:"CVE-2025-66471");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2024/06/17");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/01/21");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/01/21");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:python3-urllib3");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:amazon:linux:2");
  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("rpm.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 != "2")
{
  if (os_ver == 'A') os_ver = 'AMI';
  audit(AUDIT_OS_NOT, "Amazon Linux 2", "Amazon Linux " + os_ver);
}

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

var pkgs = [
    {'reference':'python3-urllib3-1.25.6-2.amzn2.0.4', 'release':'AL2', '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_WARNING,
      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, "python3-urllib3");
}