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    CVE-2026-40194

    phpseclib is a PHP secure communications library. Starting in 0.1.1 and prior to 3.0.51, 2.0.53, and 1.0.28, phpseclib\Net\SSH2::get_binary_packet() uses PHP's != operator to compare a received SSH packet HMAC against the locally computed HMAC. != on equal-length binary strings in PHP uses memcmp(), which short-circuits on the first differing byte. This is a real variable-time comparison (CWE-208), proven by scaling benchmarks. This vulnerability is fixed in 3.0.51, 2.0.53, and 1.0.28.

    Published:Apr 10, 2026
    Last Modified:May 8, 2026
    EPS:Apr 10, 2026
    EPSS Score:0.00013
    CVSS Score:3.7

    Affected Products

    Vendor
    Phpseclib
    Product
    Phpseclib

    Exploits

    No exploit reference

    Common Weakness Enumeration

    CWE-208 Observable Timing Discrepancy

    Related CVEs

    CVE-2026-84308 (CVSS 6.3) — phpseclib is a PHP secure communications library. Prior to 3.0.57 and 4.0.1, pure-PHP X25519 scalar multiplica…
    CVE-2026-55599 (CVSS 5.8) — phpseclib is a PHP secure communications library. From 0.1.1 until 1.0.30, 2.0.55, and 3.0.54, when an applica…
    CVE-2026-44167 (CVSS 7.5) — phpseclib is a PHP secure communications library. Prior to 1.0.29, 2.0.54, and 3.0.52, anyone loading untruste…
    CVE-2026-32935 (CVSS 8.2) — phpseclib is a PHP secure communications library. Projects using versions 0.1.1 through 1.0.26, 2.0.0 through …
    CVE-2023-52892 (CVSS 7.5) — In phpseclib before 1.0.22, 2.x before 2.0.46, and 3.x before 3.0.33, some characters in Subject Alternative N…
    CVE-2024-27355 (CVSS 7.5) — An issue was discovered in phpseclib 1.x before 1.0.23, 2.x before 2.0.47, and 3.x before 3.0.36. When process…
    CVE-2024-27354 (CVSS 7.5) — An issue was discovered in phpseclib 1.x before 1.0.23, 2.x before 2.0.47, and 3.x before 3.0.36. An attacker …
    CVE-2023-49316 (CVSS 7.5) — In Math/BinaryField.php in phpseclib 3 before 3.0.34, excessively large degrees can lead to a denial of servic…
    CVE-2023-27560 (CVSS 7.5) — Math/PrimeField.php in phpseclib 3.x before 3.0.19 has an infinite loop with composite primefields.…
    CVE-2021-30130 (CVSS 7.5) — phpseclib before 2.0.31 and 3.x before 3.0.7 mishandles RSA PKCS#1 v1.5 signature verification.…

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High