USN-8830-1: phpseclib vulnerabilities
Ubuntu fixes three phpseclib flaws covering AES timing leaks, SSH MAC comparison, and ASN.1 denial of service.
44
CVE-2026-40194
- CVSS 3.1
- 3.7 low
- EPSS
- <1%p29
- Published
- ·
- Modified
Description · NVD
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.