Amazon Linux 2023 : python3-jwt, python3-jwt+crypto (ALAS2023-2026-3298)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Amazon Linux 2023 Security Advisory ALAS2023-2026-3298.
##

include('compat.inc');

if (description)
{
  script_id(371882);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/25");

  script_cve_id(
    "CVE-2026-101917",
    "CVE-2026-101918",
    "CVE-2026-102266",
    "CVE-2026-102267",
    "CVE-2026-102268",
    "CVE-2026-102271",
    "CVE-2026-102272",
    "CVE-2026-102273",
    "CVE-2026-102275"
  );

  script_name(english:"Amazon Linux 2023 : python3-jwt, python3-jwt+crypto (ALAS2023-2026-3298)");

  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 ALAS2023-2026-3298 advisory.

    A flaw was found in PyJWT. A remote attacker can trigger a Denial of Service (DoS) through outbound
    request amplification by submitting tokens containing unknown key identifiers. Because the library does
    not cache lookup failures or enforce a minimum refresh interval when fetching signing keys, each invalid
    key identifier forces a new request to the remote JSON Web Key Set (JWKS) server. This allows an attacker
    to exhaust network resources and overwhelm the configured authentication endpoints. (CVE-2026-101917)

    A flaw was found in PyJWT. When processing a JSON Web Token (JWT) prior to signature verification, the
    parser fails to properly handle deeply nested data, leading to an unhandled recursion error. A remote
    unauthenticated attacker could exploit this flaw by submitting a specially crafted token, causing the
    application to raise an unexpected server exception and resulting in a Denial of Service (DoS).
    (CVE-2026-101918)

    A flaw was found in pyjwt. A remote attacker can forge authentication tokens and bypass security controls
    by signing tokens with an empty key. When verifying tokens against a JSON Web Key (JWK) set that contains
    an empty Hash-based Message Authentication Code (HMAC) key, the library fails to enforce key-length
    validation. This allows an attacker to generate valid tokens carrying arbitrary claims to gain
    unauthorized access. (CVE-2026-102266)

    PyJWT is a Python implementation of JSON Web Token standards. Prior to 2.14.0, PyJWT PyJWKClient is
    affected because redirect destinations are not revalidated against the JWKS trust boundary. This occurs
    when a configured trusted JWKS endpoint returns an attacker-influenced redirect. As a result, PyJWKClient
    follows the redirect and consumes the redirected response as key material. Consequently, forwarded
    credentials may be disclosed or verification keys may be substituted. This issue is fixed in version
    2.14.0. (CVE-2026-102267)

    PyJWT is a Python implementation of JSON Web Token standards. Prior to 2.14.0, is_pem_format in
    jwt/utils.py is affected because is_pem_format does not recognize every PEM representation accepted by the
    cryptography loader. This occurs when an application mixes HMAC and asymmetric algorithms and supplies a
    mutated public-key PEM as raw key bytes. As a result, HMACAlgorithm.prepare_key treats the unrecognized
    asymmetric public key as an HMAC secret. Consequently, an attacker who knows the public key can forge
    authenticated HMAC tokens. This issue is fixed in version 2.14.0. (CVE-2026-102268)

    PyJWT is a Python implementation of JSON Web Token standards. From 2.4.0 until 2.14.0, PyJWT
    HMACAlgorithm.prepare_key is affected because asymmetric-key guard relies on textual markers that are
    absent from DER encoding. This occurs when an application mixes HMAC and asymmetric algorithms and
    supplies a DER public key as the shared verification key. As a result, PyJWT uses public DER bytes as an
    HMAC secret. Consequently, an attacker who knows the public key can forge authenticated HMAC tokens. This
    issue is fixed in version 2.14.0. (CVE-2026-102271)

    PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0,
    HMACAlgorithm.prepare_key in jwt/algorithms.py is affected because raw-JWK detector does not normalize
    accepted Unicode byte-order marks before checking for JSON. This occurs when a public JWK is prefixed with
    a UTF-8 BOM and used in a mixed-algorithm verification path. As a result, public JWK bypasses asymmetric-
    key detection and becomes the HMAC secret. Consequently, an attacker who knows the public key can forge
    authenticated tokens. This issue is fixed in version 2.14.0. (CVE-2026-102272)

    PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, PyJWT
    HMACAlgorithm.prepare_key is affected because HMAC key guard only recognizes top-level public JWK forms
    and misses container representations. This occurs when an application allows HMAC and asymmetric
    algorithms and passes a public JWK container as the raw key. As a result, public asymmetric key material
    is accepted as the HMAC secret. Consequently, an attacker who knows the public key can forge a token with
    arbitrary authenticated claims. This issue is fixed in version 2.14.0. (CVE-2026-102273)

    PyJWT is a Python implementation of JSON Web Token standards. From 2.1.0 until 2.15.0, PyJWT
    OKPAlgorithm.from_jwk in  jwt/algorithms.py is affected because private-JWK import path does not compare
    the public key derived from d with x. This occurs when an OKP private JWK supplies non-corresponding x and
    d components. As a result, identity derived from x can differ from operations performed with d.
    Consequently, if an integration also accepts private key parameters from a proof header without rejecting
    them, an attacker may use a stolen sender-constrained token without the legitimate private key. This issue
    is fixed in version 2.15.0. (CVE-2026-102275)

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/ALAS2023-2026-3298.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-2026-101917.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-101918.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-102266.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-102267.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-102268.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-102271.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-102272.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-102273.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-102275.html");
  script_set_attribute(attribute:"solution", value:
"Run 'dnf update python-jwt --releasever 2023.12.20261026' or
  or 'dnf update --advisory ALAS2023-2026-3298 --releasever 2023.12.20261026' to update your system.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:C/I:C/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:N/UI:N/S:U/C:H/I:H/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-102267");

  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:"2026/09/28");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/10/24");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/10/25");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:python3-jwt");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:python3-jwt+crypto");
  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_info2.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':'python3-jwt+crypto-2.4.0-1.amzn2023.0.6', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'python3-jwt-2.4.0-1.amzn2023.0.6', '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, "python3-jwt / python3-jwt+crypto");
}