2026-04-10 20:24:06
GitHub_M
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phpseclib is a PHP secure communications library. Prior to 3.0.51, 2.0.53, and 1.0.28, phpseclibNetSSH2::get_binary_packet() uses PHPs != 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.