Bug 2457470 (CVE-2026-40194) - CVE-2026-40194 phpseclib: phpseclib: Information disclosure via timing attack in SSH HMAC comparison
Summary: CVE-2026-40194 phpseclib: phpseclib: Information disclosure via timing attack...
Keywords:
Status: NEW
Alias: CVE-2026-40194
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
low
low
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On: 2457809 2457810 2457811 2457812
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-04-10 21:01 UTC by OSIDB Bzimport
Modified: 2026-04-13 12:20 UTC (History)
0 users

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Description OSIDB Bzimport 2026-04-10 21:01:40 UTC 
phpseclib is a PHP secure communications library. 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.
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