Oracle Linux 8 : openssh (ELSA-2026-47755)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Oracle Linux Security Advisory ELSA-2026-47755.
##

include('compat.inc');

if (description)
{
  script_id(331539);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/08/01");

  script_cve_id("CVE-2026-55653", "CVE-2026-55655");

  script_name(english:"Oracle Linux 8 : openssh (ELSA-2026-47755)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Oracle Linux host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The remote Oracle Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the
ELSA-2026-47755 advisory.

    - CVE-2026-55653: Fix double free in openssh DH-GEX client path during
      FIPS known-group validation that leads to client-side denial of service
      Resolves: RHEL-185775

Tenable has extracted the preceding description block directly from the Oracle Linux 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://linux.oracle.com/errata/ELSA-2026-47755.html");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:N/C:C/I:P/A:N");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:L/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-2026-55655");

  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:"2026/06/23");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/07/31");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/08/01");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:oracle:linux:8");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:oracle:linux:8:10:baseos_patch");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:oracle:linux:openssh");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:oracle:linux:openssh-askpass");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:oracle:linux:openssh-cavs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:oracle:linux:openssh-clients");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:oracle:linux:openssh-keycat");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:oracle:linux:openssh-ldap");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:oracle:linux:openssh-server");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:oracle:linux:pam_ssh_agent_auth");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Oracle 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/OracleLinux", "Host/RedHat/release", "Host/RedHat/rpm-list", "Host/local_checks_enabled");

  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) || !pregmatch(pattern: "Oracle (?:Linux Server|Enterprise Linux)", string:os_product)) audit(AUDIT_OS_NOT, 'Oracle Linux');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'Oracle Linux');
if (! preg(pattern:"^8([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'Oracle Linux 8.x', 'Oracle Linux ' + os_version);

if (!get_kb_item('Host/RedHat/rpm-list')) 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$" && 'aarch64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Oracle Linux', cpu);

var constraints = [
  {
    'release': '8',
    'pkgs': [
      {'reference':'openssh-8.0p1-30.0.1.el8_10', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-askpass-8.0p1-30.0.1.el8_10', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-cavs-8.0p1-30.0.1.el8_10', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-clients-8.0p1-30.0.1.el8_10', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-keycat-8.0p1-30.0.1.el8_10', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-ldap-8.0p1-30.0.1.el8_10', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-server-8.0p1-30.0.1.el8_10', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'pam_ssh_agent_auth-0.10.3-7.30.0.1.el8_10', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'openssh-8.0p1-30.0.1.el8_10', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-askpass-8.0p1-30.0.1.el8_10', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-cavs-8.0p1-30.0.1.el8_10', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-clients-8.0p1-30.0.1.el8_10', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-keycat-8.0p1-30.0.1.el8_10', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-ldap-8.0p1-30.0.1.el8_10', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'openssh-server-8.0p1-30.0.1.el8_10', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
      {'reference':'pam_ssh_agent_auth-0.10.3-7.30.0.1.el8_10', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE}
    ]
  }
];

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_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, 'openssh / openssh-askpass / openssh-cavs / etc');
}