Amazon Linux 2 : openssl11 (ALAS-2026-3907)

#%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-2026-3907.
##

include('compat.inc');

if (description)
{
  script_id(345816);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/14");

  script_cve_id("CVE-2026-54874", "CVE-2026-63072");
  script_xref(name:"IAVA", value:"2026-A-0878");

  script_name(english:"Amazon Linux 2 : openssl11 (ALAS-2026-3907)");

  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 1.1.1zi-1. It is, therefore, affected by multiple
vulnerabilities as referenced in the ALAS2-2026-3907 advisory.

    Issue summary: Receiving a DTLS record for a future epoch while a handshakeis in progress causes OpenSSL
    to buffer far more memory than the recorditself requires.

    Impact summary: A peer can use a small amount of network traffic to make anOpenSSL DTLS endpoint retain a
    disproportionately large amount of memory,which may lead to a Denial of Service.

    CWE: CWE-405: Asymmetric Resource Consumption (Amplification)

    Description: While a DTLS handshake is in progress, a peer may legitimatelyhave already moved on to the
    next epoch (for example, having sent itsChangeCipherSpec and Finished messages) before the local endpoint
    hasprocessed the same transition, typically because of reordering on theunderlying UDP transport. OpenSSL
    buffers such early records so that theycan be processed once the local endpoint catches up.

    Buffering a record currently retains the entire read buffer it arrived in,which is sized to hold the
    largest possible DTLS record (around 16kilobytes), rather than just the bytes that make up the record
    itself. Upto 100 such records may be buffered per connection. As a result, a peerthat sends a stream of
    small forged records claiming to belong to the nextepoch can cause an OpenSSL DTLS endpoint to retain
    around 1.7 megabytes ofmemory, despite sending only a small fraction of that amount of data overthe
    network.

    An attacker therefore gains a memory amplification factor of around 1200,and can multiply the effect
    across as many associations as it is able toopen, making this a remote memory exhaustion Denial of Service
    risk forDTLS servers. Since the memory retained per connection remains bounded,and any limit an
    application already places on the number of concurrentassociations also bounds the total exposure, this
    issue has been assessedas Low severity.

    FIPS impact: no

    No FIPS modules are affected by this issue as the affected code is outsidethe OpenSSL FIPS module
    boundary.

    OpenSSL 4.0, 3.6, 3.5, 3.4, 3.0, 1.1.1 and 1.0.2 are vulnerable to thisissue.

    OpenSSL 4.0 users should upgrade to OpenSSL 4.0.2.OpenSSL 3.6 users should upgrade to OpenSSL
    3.6.4.OpenSSL 3.5 users should upgrade to OpenSSL 3.5.8.OpenSSL 3.4 users should upgrade to OpenSSL
    3.4.7.OpenSSL 3.0 users should upgrade to OpenSSL 3.0.22.

    Premium support customers only:OpenSSL 1.1.1 users should upgrade to OpenSSL 1.1.1ziOpenSSL 1.0.2 users
    should upgrade to OpenSSL 1.0.2zr

    This issue was reported on 18 May 2026 by Amazon Web Services.The fix has been developed by Matt Caswell.

    -- cut (non-publishing metadata for internal use) --Reported by: Amazon Web ServicesFixed by: Matt Caswell
    (CVE-2026-54874)

    Issue summary: OpenSSL CMS decryption sizes the key-unwrap output buffer basedon querying the unwrapped
    key size, but the AES-WRAP-PAD unwrap primitivecan write and cleanse more bytes than that query reports,
    causing an 8-byteout-of-bounds heap write.

    Impact summary: An attacker who supplies a crafted CMS message can trigger adeterministic 8-byte out-of-
    bounds heap write when the victim decrypts itwith CMS_decrypt(), corrupting the heap and typically
    resulting in a Denialof Service.

    CWE: CWE-787: Out-of-bounds Write

    Description: The key-wrap OID is potentially attacker-controlled on the wire.CMS unwrapping allows both
    id-aesNNN-wrap-pad and id-aesNNN-wrap ciphers.An attacker can take a legitimate message and change a
    single OID byte toselect the padded variant while leaving the message otherwise valid. Sincethe unwrap key
    is derived from the recipient's private operation (ECDH keyagreement or ML-KEM decapsulation), the RFC
    5649 integrity check cannotpass, and the decryption fails with integrity failure.

    The write is a fixed-size (8-byte), fixed-value (zero) heap overflowimmediately past the allocation,
    requires no special configuration, and isreachable from the public CMS_decrypt() function. The consequence
    isa heap corruption leading to a Denial of Service. The fix in the CMS codesizes the unwrap output buffer
    for the worst case so a failed unwrap cannotwrite past the allocation.

    FIPS impact: no

    As the CMS code lives outside the FIPS module boundary, no FIPSmodules are affected by this CVE.
    (CVE-2026-63072)

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/ALAS2-2026-3907.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-2026-54874.html");
  script_set_attribute(attribute:"see_also", value:"https://explore.alas.aws.amazon.com/CVE-2026-63072.html");
  script_set_attribute(attribute:"solution", value:
"Run 'yum update openssl11' or
  or 'yum update --advisory ALAS2-2026-3907' to update your system.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:P/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:N/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-2026-63072");

  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:"2026/08/20");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/09/14");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/14");

  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_info.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':'openssl11-1.1.1zi-1.amzn2.0.1', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-1.1.1zi-1.amzn2.0.1', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-1.1.1zi-1.amzn2.0.1', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-debuginfo-1.1.1zi-1.amzn2.0.1', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-debuginfo-1.1.1zi-1.amzn2.0.1', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-debuginfo-1.1.1zi-1.amzn2.0.1', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-devel-1.1.1zi-1.amzn2.0.1', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-devel-1.1.1zi-1.amzn2.0.1', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-devel-1.1.1zi-1.amzn2.0.1', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-libs-1.1.1zi-1.amzn2.0.1', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-libs-1.1.1zi-1.amzn2.0.1', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-libs-1.1.1zi-1.amzn2.0.1', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-static-1.1.1zi-1.amzn2.0.1', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-static-1.1.1zi-1.amzn2.0.1', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl11-static-1.1.1zi-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");
}