CentOS 9 : libevent-2.1.13-1.el9

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The package checks in this plugin were extracted from
# the CentOS Stream Build Service.
##

include('compat.inc');

if (description)
{
  script_id(348807);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/22");

  script_cve_id(
    "CVE-2026-63379",
    "CVE-2026-63381",
    "CVE-2026-63382",
    "CVE-2026-63383",
    "CVE-2026-63384",
    "CVE-2026-63385",
    "CVE-2026-63387",
    "CVE-2026-63388"
  );

  script_name(english:"CentOS 9 : libevent-2.1.13-1.el9");

  script_set_attribute(attribute:"synopsis", value:
"The remote CentOS host is missing one or more security updates for libevent.");
  script_set_attribute(attribute:"description", value:
"The remote CentOS Linux 9 host has packages installed that are affected by multiple vulnerabilities as referenced in the
libevent-2.1.13-1.el9 build changelog.

  - Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has a heap out-of-
    bounds write in bufferevent_sock.c when bufferevent_socket_set_conn_address_ copies a kernel-supplied
    AF_UNIX peer address into bufferevent_private.conn_address. Release builds compiled with NDEBUG disable
    the EVUTIL_ASSERT length guard, and the evhttp accept path can pass a 110-byte sockaddr from accept() into
    the 28-byte field. An unauthenticated local peer able to connect to an AF_UNIX listener can overwrite the
    adjacent dns_request pointer and heap data, causing memory corruption with confidentiality, integrity, and
    availability impact. This issue is fixed in versions 2.1.13 and 2.2.2-alpha. (CVE-2026-63388)

  - Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has an off-by-one
    stack buffer overflow in evdns.c when dnsname_to_labels formats a name-bearing DNS record at the end of
    the 64 KB stack buffer allocated by evdns_server_request_format_response. The final-label check permits j
    plus label_len plus one to equal buf_len, after which the terminating null byte is written to
    buf[buf_len]. A crafted DNS server response containing PTR, CNAME, MX, NS, or SOA data can trigger the
    one-byte out-of-bounds write and crash or corrupt the process. This issue is fixed in versions 2.1.13 and
    2.2.2-alpha. (CVE-2026-63387)

  - Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent processes chunked
    HTTP trailers in http.c through evhttp_read_trailer and merges them into request headers. The fix
    introduces evhttp_parse_headers_impl_ and a temporary trailer header list. An unauthenticated remote
    attacker can place security-sensitive fields in trailers so that an upstream proxy and the libevent
    application interpret different effective headers, enabling header smuggling, authorization bypass, proxy-
    header spoofing, or cache poisoning. The fix parses trailers into a temporary header list and discards
    them instead of merging them into req->input_headers. This issue is fixed in versions 2.1.13 and
    2.2.2-alpha. (CVE-2026-63379)

  - Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has a use-after-free
    in buffer.c when evbuffer_add_buffer_reference processes an output buffer whose out_total_len is zero.
    evbuffer_free_all_chains frees the initial empty chain without resetting outbuf->first, outbuf->last, or
    outbuf->last_with_datap, and APPEND_CHAIN_MULTICAST subsequently dereferences the dangling chain pointer.
    A caller that can drive this buffer state can cause memory corruption or a process crash. This issue is
    fixed in versions 2.1.13 and 2.2.2-alpha. (CVE-2026-63381)

  - Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, the libevent evhttp parser in
    http.c inconsistently handles duplicate Transfer-Encoding headers, comma-separated Transfer-Encoding
    values, and bare line feeds in chunked framing. evhttp_find_header can select only the first header,
    evhttp_check_transfer_encoding_ was absent so the previous whole-string comparison fails to recognize
    valid lists ending in chunked, and evhttp_handle_chunked_read uses EVBUFFER_EOL_CRLF rather than
    EVBUFFER_EOL_CRLF_STRICT, accepting bare LF chunk terminators. When libevent is deployed behind a proxy
    that frames the same request differently, an unauthenticated remote attacker can desynchronize request
    boundaries and smuggle a second request, potentially bypassing access controls or poisoning caches. This
    issue is fixed in versions 2.1.13 and 2.2.2-alpha. (CVE-2026-63382)

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://kojihub.stream.centos.org/koji/buildinfo?buildID=129878");
  script_set_attribute(attribute:"solution", value:
"Update the CentOS 9 Stream libevent package.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/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:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss4_vector", value:"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:L/SC:L/SI:L/SA:N");
  script_set_attribute(attribute:"cvss4_threat_vector", value:"CVSS:4.0/E:U");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-63387");
  script_set_attribute(attribute:"cvss3_score_source", value:"CVE-2026-63388");
  script_set_attribute(attribute:"cvss4_score_source", value:"CVE-2026-63385");

  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:"2026/09/16");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/22");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:centos:centos:9");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:libevent");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:libevent-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:libevent-doc");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

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

  exit(0);
}


include('rpm2.inc');
include('rhel.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) || 'CentOS' >!< os_product) audit(AUDIT_OS_NOT, 'CentOS');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'CentOS');
if (!rhel_check_release(operator: 'ge', os_version: os_version, rhel_version: '9')) audit(AUDIT_OS_NOT, 'CentOS 9.x', 'CentOS ' + os_version);

if (!get_kb_item('Host/CentOS/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$" && 's390' >!< cpu && 'aarch64' >!< cpu && 'ppc' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'CentOS', cpu);

var constraints = [
  {
    'release': '9',
    'pkgs': [
      {'reference':'libevent-2.1.13-1.el9', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'libevent-devel-2.1.13-1.el9', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'libevent-doc-2.1.13-1.el9', '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_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, 'libevent / libevent-devel / libevent-doc');
}