AlmaLinux 9 : openssh (ALSA-2026:47756)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The package checks in this plugin were extracted from
# AlmaLinux Security Advisory ALSA-2026:47756.
##

include('compat.inc');

if (description)
{
  script_id(331475);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/07/31");

  script_cve_id(
    "CVE-2026-55653",
    "CVE-2026-55654",
    "CVE-2026-55655",
    "CVE-2026-59996",
    "CVE-2026-60002"
  );
  script_xref(name:"ALSA", value:"2026:47756");
  script_xref(name:"RHSA", value:"2026:47756");

  script_name(english:"AlmaLinux 9 : openssh (ALSA-2026:47756)");

  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 9 host has packages installed that are affected by multiple vulnerabilities as referenced in the
ALSA-2026:47756 advisory.

    * openssh: Local MITM of X11 forwarding via abstract UNIX socket pre-binding in AlmaLinux OpenSSH client
    versions (CVE-2026-55655)
      * openssh: Double free in AlmaLinux versions of OpenSSH DH-GEX client path during FIPS known-group
    validation leads to client-side denial of service (CVE-2026-55653)
      * openssh: Heap out-of-bounds read in AlmaLinux versions of OpenSSH GSSAPI indicator cleanup due to
    missing NULL sentinel termination (CVE-2026-55654)
      * openssh: OpenSSH: Use-after-free vulnerability during host key re-exchange on the client side
    (CVE-2026-60002)
      * openssh: OpenSSH: `scp` file misplacement vulnerability during remote copy (CVE-2026-59996)

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/9/ALSA-2026-47756.html");
  script_set_attribute(attribute:"see_also", value:"https://access.redhat.com/errata/RHSA-2026:47756");
  script_set_attribute(attribute:"solution", value:
"Update the affected 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:N/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:"cvss_score_source", value:"CVE-2026-60002");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");
  script_cwe_id(125, 22, 415, 825, 923);

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/06/23");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/07/29");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/07/31");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alma:linux:openssh");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alma:linux:openssh-askpass");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alma:linux:openssh-clients");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alma:linux:openssh-keycat");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alma:linux:openssh-server");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alma:linux:pam_ssh_agent_auth");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alma:linux:9");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alma:linux:9::appstream");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alma:linux:9::baseos");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alma:linux:9::crb");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alma:linux:9::highavailability");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alma:linux:9::nfv");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alma:linux:9::realtime");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alma:linux:9::resilientstorage");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alma:linux:9::sap");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alma:linux:9::sap_hana");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alma:linux:9::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:"^9([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'AlmaLinux 9.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': '9',
    'pkgs': [
      {'reference':'openssh-9.9p1-9.el9_8.alma.1', 'cpu':'aarch64', 'el_string':'el9_8', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0', 'allowmaj':TRUE},
      {'reference':'openssh-9.9p1-9.el9_8.alma.1', 'cpu':'ppc64le', 'el_string':'el9_8', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0', 'allowmaj':TRUE},
      {'reference':'openssh-9.9p1-9.el9_8.alma.1', 'cpu':'s390x', 'el_string':'el9_8', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0', 'allowmaj':TRUE},
      {'reference':'openssh-9.9p1-9.el9_8.alma.1', 'cpu':'x86_64', 'el_string':'el9_8', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0', 'allowmaj':TRUE},
      {'reference':'openssh-askpass-9.9p1-9.el9_8.alma.1', 'cpu':'aarch64', 'el_string':'el9_8', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0', 'allowmaj':TRUE},
      {'reference':'openssh-askpass-9.9p1-9.el9_8.alma.1', 'cpu':'ppc64le', 'el_string':'el9_8', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0', 'allowmaj':TRUE},
      {'reference':'openssh-askpass-9.9p1-9.el9_8.alma.1', 'cpu':'s390x', 'el_string':'el9_8', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0', 'allowmaj':TRUE},
      {'reference':'openssh-askpass-9.9p1-9.el9_8.alma.1', 'cpu':'x86_64', 'el_string':'el9_8', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0', 'allowmaj':TRUE},
      {'reference':'openssh-clients-9.9p1-9.el9_8.alma.1', 'cpu':'aarch64', 'el_string':'el9_8', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0', 'allowmaj':TRUE},
      {'reference':'openssh-clients-9.9p1-9.el9_8.alma.1', 'cpu':'ppc64le', 'el_string':'el9_8', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0', 'allowmaj':TRUE},
      {'reference':'openssh-clients-9.9p1-9.el9_8.alma.1', 'cpu':'s390x', 'el_string':'el9_8', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0', 'allowmaj':TRUE},
      {'reference':'openssh-clients-9.9p1-9.el9_8.alma.1', 'cpu':'x86_64', 'el_string':'el9_8', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0', 'allowmaj':TRUE},
      {'reference':'openssh-keycat-9.9p1-9.el9_8.alma.1', 'cpu':'aarch64', 'el_string':'el9_8', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0', 'allowmaj':TRUE},
      {'reference':'openssh-keycat-9.9p1-9.el9_8.alma.1', 'cpu':'ppc64le', 'el_string':'el9_8', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0', 'allowmaj':TRUE},
      {'reference':'openssh-keycat-9.9p1-9.el9_8.alma.1', 'cpu':'s390x', 'el_string':'el9_8', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0', 'allowmaj':TRUE},
      {'reference':'openssh-keycat-9.9p1-9.el9_8.alma.1', 'cpu':'x86_64', 'el_string':'el9_8', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0', 'allowmaj':TRUE},
      {'reference':'openssh-server-9.9p1-9.el9_8.alma.1', 'cpu':'aarch64', 'el_string':'el9_8', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0', 'allowmaj':TRUE},
      {'reference':'openssh-server-9.9p1-9.el9_8.alma.1', 'cpu':'ppc64le', 'el_string':'el9_8', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0', 'allowmaj':TRUE},
      {'reference':'openssh-server-9.9p1-9.el9_8.alma.1', 'cpu':'s390x', 'el_string':'el9_8', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0', 'allowmaj':TRUE},
      {'reference':'openssh-server-9.9p1-9.el9_8.alma.1', 'cpu':'x86_64', 'el_string':'el9_8', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0', 'allowmaj':TRUE},
      {'reference':'pam_ssh_agent_auth-0.10.4-7.9.el9_8.alma.1', 'cpu':'aarch64', 'el_string':'el9_8', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
      {'reference':'pam_ssh_agent_auth-0.10.4-7.9.el9_8.alma.1', 'cpu':'ppc64le', 'el_string':'el9_8', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
      {'reference':'pam_ssh_agent_auth-0.10.4-7.9.el9_8.alma.1', 'cpu':'s390x', 'el_string':'el9_8', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
      {'reference':'pam_ssh_agent_auth-0.10.4-7.9.el9_8.alma.1', 'cpu':'x86_64', 'el_string':'el9_8', '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, 'openssh / openssh-askpass / openssh-clients / openssh-keycat / etc');
}