Amazon Linux 2 : openssl11 (ALAS-2026-3991)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Amazon Linux 2 Security Advisory ALAS-2026-3991.
##

include('compat.inc');

if (description)
{
  script_id(365208);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/12");

  script_cve_id(
    "CVE-2026-35189",
    "CVE-2026-54872",
    "CVE-2026-75806",
    "CVE-2026-84782"
  );
  script_xref(name:"IAVA", value:"2026-A-1072");

  script_name(english:"Amazon Linux 2 : openssl11 (ALAS-2026-3991)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Amazon Linux 2 host is missing a security update.");
  script_set_attribute(attribute:"description", value:
"The version of openssl11 installed on the remote host is prior to 1.1.1zj-1. It is, therefore, affected by multiple
vulnerabilities as referenced in the ALAS2-2026-3991 advisory.

    Issue summary: A certificate with many nameRelativeToCRLIssuer CRLdistribution points causes
    disproportionate heap growth when OpenSSL cachesX.509 extensions.

    Impact summary: Receiving a crafted certificate from a malicious peer can leadto significant memory
    pressure and possible Denial of Service in clients orin servers that solicit client certificates.

    CWE: CWE-770: Allocation of Resources Without Limits or Throttling

    Description: A certificate or a set of certificates that fits under the limit forsize of certificates
    accepted from the peer (~100 KiB) can result in allocationof several hundred MiB of resident memory on the
    receiving sideduring a normal TLS handshake.  This may be enough to crash the client orserver, if multiple
    concurrent connections lead to similarly large memoryallocations.

    The fix postpones processing of the CRL distribution points extensions incertificates to the time when the
    processed value is required for CRL processing.This avoids keeping large memory allocations for a long
    time when suchcertificates are received.

    FIPS impact: noThe affected code is outside the FIPS module boundary. (CVE-2026-35189)

    Issue summary: The generic elliptic-curve scalar multiplication used forECDSA and SM2 signature operations
    with curves that do not have a dedicatedimplementation leaks information about the secret nonce through
    timing.

    Impact summary: An attacker able to measure signing times may learninformation about the per-signature
    secret nonce, which over many signaturescan, via a lattice / Hidden Number Problem attack, lead to
    recovery of theprivate key.

    CWE: CWE-208: Observable Timing Discrepancy

    Description: The generic elliptic-curve scalar multiplication used forcurves that do not have a dedicated
    constant-time implementation pads thesecret scalar with non-constant-time BIGNUM operations, so the time
    takendepends on the value of the secret scalar derived from the ECDSA and SM2 nonce.

    The leak is very small; observing it requires a large number ofmeasurements. The effect is largest for
    curves whose group order lieson a machine-word boundary, such as brainpoolP384r1.

    Applications using ECDSA signing over the Brainpool and other generic primecurves, and SM2 signing on
    platforms that use the generic implementation,are vulnerable to this issue.

    The NIST curves P-256, P-384 and P-521 use dedicated constant-timeimplementations and are not affected.

    FIPS Impact: noThe FIPS modules are not affected: the approved NIST curves used in the FIPSprovider have
    dedicated constant-time implementations and do not use theaffected code path. (CVE-2026-54872)

    Issue summary: An established DTLS 1.2 association using an AEAD cipher suitecan be terminated by a single
    unauthenticated datagram whose encryptedfragment is shorter than the mandatory explicit IV and
    authentication tagoverhead.

    Impact summary: An attacker who can send a datagram that is routed to anexisting DTLS 1.2 association can
    tear that association down without knowingany key material. This is a Denial of Service limited to the
    targetedassociation. There is no memory safety or confidentiality impact.

    CWE: CWE-1284: Improper Validation of Specified Quantity in Input

    Description: In TLS 1.2 and DTLS 1.2 every record protected by an AEAD ciphersuite carries an explicit IV
    followed by the ciphertext and an authenticationtag. When decrypting such a record the record layer passed
    the record length tothe cipher implementation before checking that the record was long enough tocontain
    the explicit IV and the tag. For a record shorter than that overhead thecipher implementation rejected the
    impossible length, and the record layertreated this as an internal failure and raised a fatal
    internal_error alertinstead of treating the record as one that failed authentication.

    In TLS 1.2 the same record causes a fatal internal_error alert instead of theexpected bad_record_mac
    alert. Since any undecryptable record alreadyterminates a TLS connection, this is a protocol conformance
    issue rather thana security issue in TLS.

    The fix validates the record length against the explicit IV and tag lengthbefore any AEAD processing, so
    that TLS reports bad_record_mac and DTLSsilently discards the record.

    FIPS impact: noThe affected code is outside the FIPS module boundary. (CVE-2026-75806)

    A flaw was found in OpenSSL. The Datagram Transport Layer Security (DTLS) retransmission mechanism fails
    to properly handle handshake message writes that are suspended before completion. A remote attacker could
    exploit this vulnerability during handshake message retransmission, causing OpenSSL to read past the
    message buffer or overwrite internal state required to resume writing. This issue can result in
    information disclosure through out-of-bounds memory reads or cause a Denial of Service (DoS) by crashing
    the process. (CVE-2026-84782)

Tenable has extracted the preceding description block directly from the tested product 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://alas.aws.amazon.com//AL2/ALAS2-2026-3991.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/faqs.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-35189.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-54872.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-75806.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-84782.html");
  script_set_attribute(attribute:"solution", value:
"Run 'yum update openssl11' or
  or 'yum update --advisory ALAS2-2026-3991' to update your system.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/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:L/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-2026-84782");

  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:"2026/09/29");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/10/12");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/10/12");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssl11");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssl11-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssl11-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssl11-libs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssl11-static");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:amazon:linux:2");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_set_attribute(attribute:"stig_severity", value:"I");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Amazon 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_info2.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/AmazonLinux/release", "Host/AmazonLinux/rpm-list");

  exit(0);
}

include("rpm2.inc");

if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);

var alas_release = get_kb_item("Host/AmazonLinux/release");
if (isnull(alas_release) || !strlen(alas_release)) audit(AUDIT_OS_NOT, "Amazon Linux");
var os_ver = pregmatch(pattern: "^AL(A|\d+|-\d+)", string:alas_release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, "Amazon Linux");
os_ver = os_ver[1];
if (os_ver != "2")
{
  if (os_ver == 'A') os_ver = 'AMI';
  audit(AUDIT_OS_NOT, "Amazon Linux 2", "Amazon Linux " + os_ver);
}

if (!get_kb_item("Host/AmazonLinux/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING);

var pkgs = [
    {'reference':'openssl11-1.1.1zj-1.amzn2.0.1', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-1.1.1zj-1.amzn2.0.1', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-1.1.1zj-1.amzn2.0.1', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-debuginfo-1.1.1zj-1.amzn2.0.1', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-debuginfo-1.1.1zj-1.amzn2.0.1', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-debuginfo-1.1.1zj-1.amzn2.0.1', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-devel-1.1.1zj-1.amzn2.0.1', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-devel-1.1.1zj-1.amzn2.0.1', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-devel-1.1.1zj-1.amzn2.0.1', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-libs-1.1.1zj-1.amzn2.0.1', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-libs-1.1.1zj-1.amzn2.0.1', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-libs-1.1.1zj-1.amzn2.0.1', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-static-1.1.1zj-1.amzn2.0.1', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-static-1.1.1zj-1.amzn2.0.1', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-static-1.1.1zj-1.amzn2.0.1', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE}
];

var flag = 0;
foreach var package_array ( pkgs ) {
  var reference = NULL;
  var _release = NULL;
  var sp = NULL;
  var _cpu = NULL;
  var el_string = NULL;
  var rpm_spec_vers_cmp = NULL;
  var epoch = NULL;
  var allowmaj = NULL;
  var exists_check = NULL;
  var cves = NULL;
  if (!empty_or_null(package_array['reference'])) reference = package_array['reference'];
  if (!empty_or_null(package_array['release'])) _release = package_array['release'];
  if (!empty_or_null(package_array['sp'])) sp = package_array['sp'];
  if (!empty_or_null(package_array['cpu'])) _cpu = package_array['cpu'];
  if (!empty_or_null(package_array['el_string'])) el_string = package_array['el_string'];
  if (!empty_or_null(package_array['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = package_array['rpm_spec_vers_cmp'];
  if (!empty_or_null(package_array['epoch'])) epoch = package_array['epoch'];
  if (!empty_or_null(package_array['allowmaj'])) allowmaj = package_array['allowmaj'];
  if (!empty_or_null(package_array['exists_check'])) exists_check = package_array['exists_check'];
  if (!empty_or_null(package_array['cves'])) cves = package_array['cves'];
  if (reference && _release && (!exists_check || rpm_exists(release:_release, rpm:exists_check))) {
    if (rpm_check(release:_release, 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, "openssl11 / openssl11-debuginfo / openssl11-devel / etc");
}