Vulnerability Description
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 Score
LOW
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Phpseclib | Phpseclib | <= 1.0.27 |
Related Weaknesses (CWE)
References
- https://github.com/phpseclib/phpseclib/commit/ffe48b6b1b1af6963327f0a5330e3aa004Patch
- https://github.com/phpseclib/phpseclib/releases/tag/1.0.28Release Notes
- https://github.com/phpseclib/phpseclib/releases/tag/2.0.53Release Notes
- https://github.com/phpseclib/phpseclib/releases/tag/3.0.51Release Notes
- https://github.com/phpseclib/phpseclib/security/advisories/GHSA-r854-jrxh-36qxVendor Advisory
- https://github.com/phpseclib/phpseclib/security/advisories/GHSA-r854-jrxh-36qxVendor Advisory
FAQ
What is CVE-2026-40194?
CVE-2026-40194 is a vulnerability with a CVSS score of 3.7 (LOW). 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 pa...
How severe is CVE-2026-40194?
CVE-2026-40194 has been rated LOW with a CVSS base score of 3.7/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-40194?
Check the references section above for vendor advisories and patch information. Affected products include: Phpseclib Phpseclib.