EulerOS 2.0 SP15 : libssh2 (EulerOS-SA-2026-3987)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(364042);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/08");

  script_cve_id(
    "CVE-2025-15661",
    "CVE-2026-55199",
    "CVE-2026-58050",
    "CVE-2026-58051",
    "CVE-2026-66032",
    "CVE-2026-66033",
    "CVE-2026-66034",
    "CVE-2026-66035"
  );
  script_xref(name:"IAVA", value:"2026-A-0788");

  script_name(english:"EulerOS 2.0 SP15 : libssh2 (EulerOS-SA-2026-3987)");

  script_set_attribute(attribute:"synopsis", value:
"The remote EulerOS host is missing multiple security updates.");
  script_set_attribute(attribute:"description", value:
"According to the versions of the libssh2 packages installed, the EulerOS installation on the remote host is affected by
the following vulnerabilities :

    libssh2 through 1.11.1 reads an attacker-controlled 32-bit attribute count from a publickey-subsystem
    response and uses it in the allocation num_attrs * sizeof(libssh2_publickey_attribute) without bounds
    checking, so on 32-bit platforms the multiplication overflows to an undersized buffer. A malicious SSH
    server can then drive the attribute-parsing loop to write past the allocation, causing a heap buffer
    overflow in a connecting libssh2 client.(CVE-2026-58050)

    libssh2 through 1.11.1, fixed in commit a13bb6c, contains a missing bounds check vulnerability that allows
    a malicious SSH server to trigger an arbitrary-length heap out-of-bounds read and a free of an
    uninitialized pointer via the publickey subsystem. In libssh2_publickey_list_fetch(), the version 1
    response parser reads a server-controlled comment_len value and advances the parse pointer without
    verifying sufficient bytes remain in the buffer, causing the out-of-bounds read to leak heap pointers from
    adjacent allocations defeating ASLR, followed by heap allocator state corruption when the error cleanup
    path frees an uninitialized pointer from a non-zeroed realloc() region.(CVE-2026-66034)

    libssh2 through 1.11.1 grows its publickey list with SSH2_REALLOC but does not zero-initialize new entries
    before parsing populates them, so a parse failure reaching the cleanup path leaves
    libssh2_publickey_list_free operating on an uninitialized entry. A malicious SSH server offering the
    publickey subsystem can use a malformed response to make cleanup free an uninitialized, attacker-
    influenceable attrs pointer in a connecting libssh2 client.(CVE-2026-58051)

    libssh2 through 1.11.1, fixed in commit 5e47761, contains a double-free vulnerability in the sftp_open()
    function in src/sftp.c that allows a malicious SSH server to corrupt the heap of any authenticated client
    opening an SFTP session. When a server responds to SSH_FXP_OPEN with SSH_FXP_STATUS containing FX_OK, the
    response data buffer is freed, and if a subsequent sftp_packet_require() call returns a specific error
    such as LIBSSH2_ERROR_CHANNEL_PACKET_EXCEEDED, the same pointer is freed a second time, enabling tcache
    dup conditions on glibc systems that allow overlapping allocations and function pointer
    overwrites.(CVE-2026-66032)

    libssh2 through 1.11.1, fixed in commit 2dae302, contains an out-of-bounds heap read vulnerability in the
    sftp_symlink() function in src/sftp.c that allows a malicious SSH server or man-in-the-middle attacker to
    disclose heap memory contents or cause a crash by sending a crafted SSH_FXP_NAME response. Attackers can
    supply a link_len value larger than the actual packet data in SSH_FXP_NAME responses for SFTP READLINK and
    REALPATH operations, triggering a heap buffer over-read of up to target_len minus one bytes due to the
    missing validation of available packet buffer size before the memcpy operation.(CVE-2025-15661)

    libssh2 through 1.11.1, fixed in commit a2ed82d, contains a pre-authentication integer underflow
    vulnerability in the ssh2_cipher_crypt() function in src/openssl.c that allows a malicious SSH server to
    crash any connecting client by negotiating AES-GCM ciphers during handshake. Attackers can exploit the
    underflow in the expression computing blocksize minus aadlen minus authentication tag length to trigger an
    out-of-bounds read and a memcpy call with a near-SIZE_MAX length argument, causing immediate process crash
    before any authentication occurs.(CVE-2026-66033)

    libssh2 through 1.11.1, fixed in commit 1762685, contains a pre-authentication denial of service
    vulnerability in the SSH_MSG_EXT_INFO handler in src/packet.c that allows a malicious SSH server to cause
    a client CPU exhaustion loop by sending a crafted extension count value. A malicious server can set
    nr_extensions to 0xFFFFFFFF during key exchange, causing the client to spin in a tight CPU loop for over
    60 seconds because return values from _libssh2_get_string() are unchecked and the session timeout does not
    apply to CPU-bound loops.(CVE-2026-55199)

    libssh2 through 1.11.1, fixed in commit 42e33d8, contains a pre-authentication heap buffer overflow
    vulnerability that allows a malicious SSH server to corrupt heap metadata in any connecting client by
    sending a packet with a packet_length smaller than the cipher's block size during Encrypt-then-MAC cipher
    negotiation. In the fullpacket() function in src/transport.c, the ETM path allocates a buffer of
    packet_length bytes but copies blocksize minus one bytes via memcpy, causing an overflow that on 32-bit
    glibc writes attacker-controlled bytes into an adjacent chunk's SIZE field, enabling tcache bin confusion,
    overlapping live objects, and function pointer overwrite during the session handshake before
    authentication.(CVE-2026-66035)

Tenable has extracted the preceding description block directly from the EulerOS libssh2 security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  # https://developer.huaweicloud.com/ict/en/site-euleros/euleros/security-advisories/EulerOS-SA-2026-3987
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?92b08cbd");
  script_set_attribute(attribute:"solution", value:
"Update the affected libssh2 packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:H/Au:N/C:P/I:N/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss4_vector", value:"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N");
  script_set_attribute(attribute:"cvss4_threat_vector", value:"CVSS:4.0/E:P");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2025-15661");
  script_set_attribute(attribute:"cvss4_score_source", value:"CVE-2026-66033");

  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:"2026/06/17");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/10/08");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/10/08");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:huawei:euleros:libssh2");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:huawei:euleros:libssh2-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:huawei:euleros:libssh2-help");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:huawei:euleros:2.0");
  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:"Huawei 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/cpu", "Host/EulerOS/release", "Host/EulerOS/rpm-list", "Host/EulerOS/sp");
  script_exclude_keys("Host/EulerOS/uvp_version");

  exit(0);
}

include("rpm.inc");

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

var _release = get_kb_item("Host/EulerOS/release");
if (isnull(_release) || _release !~ "^EulerOS") audit(AUDIT_OS_NOT, "EulerOS");
var uvp = get_kb_item("Host/EulerOS/uvp_version");
if (_release !~ "^EulerOS release 2\.0(\D|$)") audit(AUDIT_OS_NOT, "EulerOS 2.0 SP15");

var sp = get_kb_item("Host/EulerOS/sp");
if (isnull(sp) || sp !~ "^(15)$") audit(AUDIT_OS_NOT, "EulerOS 2.0 SP15");

if (!empty_or_null(uvp)) audit(AUDIT_OS_NOT, "EulerOS 2.0 SP15", "EulerOS UVP " + uvp);

if (!get_kb_item("Host/EulerOS/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 && "x86" >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, "EulerOS", cpu);
if ("aarch64" >!< cpu) audit(AUDIT_ARCH_NOT, "aarch64", cpu);

var flag = 0;

var pkgs = [
  "libssh2-1.11.0-5.h21510.12.eulerosv2r15",
  "libssh2-devel-1.11.0-5.h21510.12.eulerosv2r15",
  "libssh2-help-1.11.0-5.h21510.12.eulerosv2r15"
];

foreach (var pkg in pkgs)
  if (rpm_check(release:"EulerOS-2.0", sp:"15", reference:pkg)) 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, "libssh2");
}