Ubuntu 24.04 LTS / 25.10 / 26.04 LTS : libssh2 vulnerabilities (USN-8486-1)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-8486-1. 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(325003);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/07/03");

  script_cve_id("CVE-2025-15661", "CVE-2026-55199", "CVE-2026-55200");
  script_xref(name:"USN", value:"8486-1");

  script_name(english:"Ubuntu 24.04 LTS / 25.10 / 26.04 LTS : libssh2 vulnerabilities (USN-8486-1)");

  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 24.04 LTS / 25.10 / 26.04 LTS host has packages installed that are affected by multiple
vulnerabilities as referenced in the USN-8486-1 advisory.

    It was discovered that libssh2 incorrectly handled the sftp_symlink() function. A malicious SSH server or
    machine-in-the-middle attacker could possibly use this issue to obtain sensitive information or cause a
    denial of service. (CVE-2025-15661)

    It was discovered that libssh2 had a pre-authentication denial of service vulnerability in the
    SSH_MSG_EXT_INFO handler. A malicious SSH server could possibly use this issue to cause a client CPU
    exhaustion loop, resulting in a denial of service. (CVE-2026-55199)

    It was discovered that libssh2 incorrectly handled packet length fields. A remote attacker could possibly
    use this issue to execute arbitrary code. This issue only affected Ubuntu 25.10 and Ubuntu 26.04 LTS.
    (CVE-2026-55200)

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-8486-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected libssh2-1-dev and / or libssh2-1t64 packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:P");
  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:R/S:U/C:H/I:H/A:L");
  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:H/VI:H/VA:H/SC:N/SI:N/SA:N");
  script_set_attribute(attribute:"cvss4_threat_vector", value:"CVSS:4.0/E:P");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-55200");

  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:"2026/06/17");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/06/30");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/07/03");

  script_set_attribute(attribute:"plugin_type", value:"local");
  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:25.10");
  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:libssh2-1-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libssh2-1t64");
  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_info.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 (! ('24.04' >< os_release || '25.10' >< os_release || '26.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 24.04 / 25.10 / 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': '24.04', 'pkgname': 'libssh2-1-dev', 'pkgver': '1.11.0-4.1ubuntu0.24.04.2', 'cves': ['CVE-2025-15661', 'CVE-2026-55199']},
    {'osver': '24.04', 'pkgname': 'libssh2-1t64', 'pkgver': '1.11.0-4.1ubuntu0.24.04.2', 'cves': ['CVE-2025-15661', 'CVE-2026-55199']},
    {'osver': '25.10', 'pkgname': 'libssh2-1-dev', 'pkgver': '1.11.1-1ubuntu0.25.10.2', 'cves': ['CVE-2025-15661', 'CVE-2026-55199', 'CVE-2026-55200']},
    {'osver': '25.10', 'pkgname': 'libssh2-1t64', 'pkgver': '1.11.1-1ubuntu0.25.10.2', 'cves': ['CVE-2025-15661', 'CVE-2026-55199', 'CVE-2026-55200']},
    {'osver': '26.04', 'pkgname': 'libssh2-1-dev', 'pkgver': '1.11.1-1ubuntu0.26.04.2', 'cves': ['CVE-2025-15661', 'CVE-2026-55199', 'CVE-2026-55200']},
    {'osver': '26.04', 'pkgname': 'libssh2-1t64', 'pkgver': '1.11.1-1ubuntu0.26.04.2', 'cves': ['CVE-2025-15661', 'CVE-2026-55199', 'CVE-2026-55200']}
];

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, 'libssh2-1-dev / libssh2-1t64');
}