CVE-2026-40194

LOW 3.7EPSS 0.4%

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.

CVSS v3.1: 3.7 LOWCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
CVSS v3.1: 3.7 LOWCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
EPSS: 0.36% chance of exploitation in the next 30 days, 29th percentile
Published: 2026-04-10
Updated: 2026-05-08

Proof-of-concept exploits (1)

advisories/GHSA-r854-jrxh-36qx

References

CVE Record
NVD entry

CVE-2026-40194

Proof-of-concept exploits (1)

References

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