AlmaLinux 10 : libssh (ALSA-2026:55855)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The package checks in this plugin were extracted from
# AlmaLinux Security Advisory ALSA-2026:55855.
##

include('compat.inc');

if (description)
{
  script_id(337665);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/08/18");

  script_cve_id(
    "CVE-2026-15370",
    "CVE-2026-59842",
    "CVE-2026-59843",
    "CVE-2026-59844",
    "CVE-2026-59845",
    "CVE-2026-59846",
    "CVE-2026-59847",
    "CVE-2026-59848",
    "CVE-2026-59849",
    "CVE-2026-59850",
    "CVE-2026-59851"
  );
  script_xref(name:"ALSA", value:"2026:55855");
  script_xref(name:"RHSA", value:"2026:55855");

  script_name(english:"AlmaLinux 10 : libssh (ALSA-2026:55855)");

  script_set_attribute(attribute:"synopsis", value:
"The remote AlmaLinux host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The remote AlmaLinux 10 host has packages installed that are affected by multiple vulnerabilities as referenced in the
ALSA-2026:55855 advisory.

    * libssh: libssh: information disclosure via short GSSAPI Curve25519 public key (CVE-2026-59842)
      * libssh: libssh: denial of service via zero advertised channel packet size (CVE-2026-59843)
      * libssh: libssh: denial of service via oversized SFTP read length (CVE-2026-59844)
      * libssh: libssh: denial of service via unchecked ProxyCommand fork() failure (CVE-2026-59845)
      * libssh: libssh: information disclosure via ProxyCommand %r username expansion (CVE-2026-59846)
      * libssh: libssh: integrity downgrade via OpenSSL AES-GCM tag verification (CVE-2026-59847)
      * libssh: libssh: denial of service via SFTP responses with unknown request IDs (CVE-2026-59848)
      * libssh: libssh: denial of service via automatic certificate authentication loop (CVE-2026-59849)
      * libssh: libssh: use-after-free via data callbacks on closed channels (CVE-2026-59850)
      * libssh: libssh: authentication bypass via missing GSSAPI principal check (CVE-2026-59851)
      * libssh: libssh: stack buffer overflow in SFTP server longname construction (CVE-2026-15370)

Tenable has extracted the preceding description block directly from the AlmaLinux 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://errata.almalinux.org/10/ALSA-2026-55855.html");
  script_set_attribute(attribute:"see_also", value:"https://access.redhat.com/errata/RHSA-2026:55855");
  script_set_attribute(attribute:"solution", value:
"Update the affected libssh, libssh-config and / or libssh-devel packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:C/A:N");
  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:H/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-59847");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");
  script_cwe_id(121, 125, 253, 390, 416, 770, 78, 789, 835, 863);

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/07/21");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/08/17");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/08/18");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alma:linux:libssh");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alma:linux:libssh-config");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alma:linux:libssh-devel");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alma:linux:10");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alma:linux:10::appstream");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alma:linux:10::baseos");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alma:linux:10::highavailability");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alma:linux:10::nfv");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alma:linux:10::powertools");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alma:linux:10::realtime");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alma:linux:10::resilientstorage");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alma:linux:10::sap");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alma:linux:10::sap_hana");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alma:linux:10::supplementary");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Alma 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/AlmaLinux/release", "Host/AlmaLinux/rpm-list", "Host/cpu");

  exit(0);
}


include('rpm2.inc');

if (!get_kb_item('Host/local_checks_enabled')) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_product = get_kb_item('installed_os/local/SSH/0/product');
if (isnull(os_product) || 'AlmaLinux' >!< os_product) audit(AUDIT_OS_NOT, 'AlmaLinux');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'AlmaLinux');
if (! preg(pattern:"^10([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'AlmaLinux 10.x', 'AlmaLinux ' + os_version);

if (!get_kb_item('Host/AlmaLinux/rpm-list')) audit(AUDIT_PACKAGE_LIST_MISSING);

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

var constraints = [
  {
    'release': '10',
    'pkgs': [
      {'reference':'libssh-0.12.0-3.el10_2', 'cpu':'aarch64', 'el_string':'el10_2', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
      {'reference':'libssh-0.12.0-3.el10_2', 'cpu':'ppc64le', 'el_string':'el10_2', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
      {'reference':'libssh-0.12.0-3.el10_2', 'cpu':'s390x', 'el_string':'el10_2', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
      {'reference':'libssh-0.12.0-3.el10_2', 'cpu':'x86_64', 'el_string':'el10_2', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
      {'reference':'libssh-0.12.0-3.el10_2', 'cpu':'x86_64_v2', 'el_string':'el10_2', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
      {'reference':'libssh-config-0.12.0-3.el10_2', 'el_string':'el10_2', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
      {'reference':'libssh-devel-0.12.0-3.el10_2', 'cpu':'aarch64', 'el_string':'el10_2', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
      {'reference':'libssh-devel-0.12.0-3.el10_2', 'cpu':'ppc64le', 'el_string':'el10_2', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
      {'reference':'libssh-devel-0.12.0-3.el10_2', 'cpu':'s390x', 'el_string':'el10_2', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
      {'reference':'libssh-devel-0.12.0-3.el10_2', 'cpu':'x86_64', 'el_string':'el10_2', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
      {'reference':'libssh-devel-0.12.0-3.el10_2', 'cpu':'x86_64_v2', 'el_string':'el10_2', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'}
    ]
  }
];

var os_release = get_one_kb_item('installed_os/local/SSH/0/release');
var os_sp = get_one_kb_item('Host/*/minor_release');

var flag = 0;
var reference;
var sp;
var _cpu;
var el_string;
var rpm_spec_vers_cmp;
var epoch;
var allowmaj;
var exists_check;
var cves;
foreach var constraint ( constraints ) {
  # Check that the target release is equal to the affected release
  if (!empty_or_null(constraint['release'])){
    if (constraint['release'] != os_release) continue;
  }
  if (!empty_or_null(constraint['sp'])){
    if (constraint['sp'] != os_sp) continue;
  }
  foreach var pkg ( constraint['pkgs'] ) {
    reference = NULL;
    sp = NULL;
    _cpu = NULL;
    el_string = NULL;
    rpm_spec_vers_cmp = NULL;
    epoch = NULL;
    allowmaj = NULL;
    exists_check = NULL;
    cves = NULL;
    if (!empty_or_null(pkg['reference'])) reference = pkg['reference'];
    if (!empty_or_null(pkg['sp'])) sp = pkg['sp'];
    if (!empty_or_null(pkg['cpu'])) _cpu = pkg['cpu'];
    if (!empty_or_null(pkg['el_string'])) el_string = pkg['el_string'];
    if (!empty_or_null(pkg['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = pkg['rpm_spec_vers_cmp'];
    if (!empty_or_null(pkg['epoch'])) epoch = pkg['epoch'];
    if (!empty_or_null(pkg['allowmaj'])) allowmaj = pkg['allowmaj'];
    if (!empty_or_null(pkg['exists_check'])) exists_check = pkg['exists_check'];
    if (!empty_or_null(pkg['cves'])) cves = pkg['cves'];
    if (reference &&
        ## (no known rpm to check OR known rpm_exists)
        (!exists_check || rpm_exists(rpm:exists_check)) &&
        rpm_check(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, 'libssh / libssh-config / libssh-devel');
}