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CVE-2026-40194

phpseclib has a variable-time HMAC comparison in SSH2::get_binary_packet() using != instead of hash_equals() PUBLISHED

Description (CNA)

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.

Affected (CNA)

Vendor / productVersions
phpseclib / phpseclibaffected >= 0.1.1, < 1.0.28; affected >= 2.0.0, < 2.0.53; affected >= 3.0.0, < 3.0.51

CWE

CWE-208

References

ADP enrichment

CISA-ADP

No English description supplied.