low3.7
CVE-2026-40194
phpseclib has a variable-time HMAC comparison in SSH2::get_binary_packet() using != instead of hash_equals()
Impact
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 packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| composer | phpseclib/phpseclib | >= 2.0.0, < 2.0.53 | 2.0.53 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Phpseclib | Phpseclib | through 1.0.27 from 2.0.0 before 2.0.53 from 3.0.0 before 3.0.51 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-r854-jrxh-36qx
- https://github.com/phpseclib/phpseclib/security/advisories/GHSA-r854-jrxh-36qx
- https://github.com/phpseclib/phpseclib/commit/ffe48b6b1b1af6963327f0a5330e3aa004a194ac
- https://github.com/phpseclib/phpseclib/releases/tag/1.0.28
- https://github.com/phpseclib/phpseclib/releases/tag/2.0.53
- https://github.com/phpseclib/phpseclib/releases/tag/3.0.51
- https://nvd.nist.gov/vuln/detail/CVE-2026-40194