Ubuntu 22.04 LTS / 24.04 LTS / 26.04 LTS : pyasn1 vulnerabilities (USN-8712-1)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-8712-1. The text
# itself is copyright (C) Canonical, Inc. See
# <https://ubuntu.com/security/notices>. Ubuntu(R) is a registered
# trademark of Canonical, Inc.
##

include('compat.inc');

if (description)
{
  script_id(365396);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/13");

  script_cve_id("CVE-2026-59884", "CVE-2026-59885", "CVE-2026-59886");
  script_xref(name:"USN", value:"8712-1");

  script_name(english:"Ubuntu 22.04 LTS / 24.04 LTS / 26.04 LTS : pyasn1 vulnerabilities (USN-8712-1)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Ubuntu host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The remote Ubuntu 22.04 LTS / 24.04 LTS / 26.04 LTS host has packages installed that are affected by multiple
vulnerabilities as referenced in the USN-8712-1 advisory.

    It was discovered that pyasn1 did not properly bound the size of long-form tag identifiers when parsing
    BER, CER, or DER encoded data. An attacker could possibly use this issue to cause applications decoding
    untrusted ASN.1 data to consume excessive CPU resources, resulting in a denial of service.
    (CVE-2026-59884)

    It was discovered that pyasn1 processed OBJECT IDENTIFIER and RELATIVE-OID values in quadratic time
    relative to the number of arcs. An attacker could possibly use this issue to cause applications decoding
    untrusted ASN.1 data to consume excessive CPU resources, resulting in a denial of service.
    (CVE-2026-59885)

    It was discovered that pyasn1 incorrectly handled conversion of decoded REAL values to Python float types.
    An attacker could possibly use this issue to cause applications decoding untrusted ASN.1 data to consume
    excessive CPU and memory resources, resulting in a denial of service. (CVE-2026-59886)

Tenable has extracted the preceding description block directly from the Ubuntu 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://ubuntu.com/security/notices/USN-8712-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected pypy-pyasn1 and / or python3-pyasn1 packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:N/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:N/S:U/C:N/I:N/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-2026-59886");

  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:"2026/07/14");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/09/01");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/10/13");

  script_set_attribute(attribute:"plugin_type", value:"local");
  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:"p-cpe:/a:canonical:ubuntu_linux:pypy-pyasn1");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3-pyasn1");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

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

  script_copyright(english:"Ubuntu Security Notice (C) 2026 Canonical, Inc. / NASL script (C) 2026 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info2.nasl");
  script_require_keys("Host/cpu", "Host/Ubuntu", "Host/Ubuntu/release", "Host/Debian/dpkg-l");

  exit(0);
}

include('debian_package.inc');

if ( ! get_kb_item('Host/local_checks_enabled') ) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_release = get_kb_item('Host/Ubuntu/release');
if ( isnull(os_release) ) audit(AUDIT_OS_NOT, 'Ubuntu');
os_release = chomp(os_release);
if (! ('22.04' >< os_release || '24.04' >< os_release || '26.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 22.04 / 24.04 / 26.04', 'Ubuntu ' + os_release);
if ( ! get_kb_item('Host/Debian/dpkg-l') ) audit(AUDIT_PACKAGE_LIST_MISSING);

var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('x86_64' >!< cpu && cpu !~ "^i[3-6]86$" && 's390' >!< cpu && 'aarch64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Ubuntu', cpu);

var pkgs = [
    {'osver': '22.04', 'pkgname': 'pypy-pyasn1', 'pkgver': '0.4.8-1ubuntu0.3'},
    {'osver': '22.04', 'pkgname': 'python3-pyasn1', 'pkgver': '0.4.8-1ubuntu0.3'},
    {'osver': '24.04', 'pkgname': 'python3-pyasn1', 'pkgver': '0.4.8-4ubuntu0.3'},
    {'osver': '26.04', 'pkgname': 'python3-pyasn1', 'pkgver': '0.6.3-1ubuntu0.1'}
];

var flag = 0;
foreach var package_array ( pkgs ) {
  var osver = NULL;
  var pkgname = NULL;
  var pkgver = NULL;
  if (!empty_or_null(package_array['osver'])) osver = package_array['osver'];
  if (!empty_or_null(package_array['pkgname'])) pkgname = package_array['pkgname'];
  if (!empty_or_null(package_array['pkgver'])) pkgver = package_array['pkgver'];
  if (!empty_or_null(package_array['cves'])) cves = package_array['cves'];
  if (osver && pkgname && pkgver) {
    if (deb_check(release:osver, prefix:pkgname, reference:pkgver, cves:cves)) flag++;
  }
}

if (flag)
{
  var extra = '';
  extra += ubuntu_report_get();
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    extra      : extra
  );
  exit(0);
}
else
{
  var tested = ubuntu_pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'pypy-pyasn1 / python3-pyasn1');
}