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, 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.
Weakness
Two separate operations in a product require different amounts of time to complete, in a way that is observable to an actor and reveals security-relevant information about the state of the product, such as whether a particular operation was successful or not.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Phpseclib | Phpseclib | * | 1.0.27 (including) |
| Phpseclib | Phpseclib | 2.0.0 (including) | 2.0.53 (excluding) |
| Phpseclib | Phpseclib | 3.0.0 (including) | 3.0.51 (excluding) |
| Php-phpseclib | Ubuntu | esm-apps/xenial | * |
| Php-phpseclib | Ubuntu | questing | * |
| Php-phpseclib | Ubuntu | upstream | * |
| Php-phpseclib3 | Ubuntu | questing | * |
| Php-phpseclib3 | Ubuntu | upstream | * |
| Phpseclib | Ubuntu | esm-apps/xenial | * |
| Phpseclib | Ubuntu | questing | * |
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/462.html
- https://cwe.mitre.org/data/definitions/541.html
- https://cwe.mitre.org/data/definitions/580.html
References
- 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://github.com/phpseclib/phpseclib/security/advisories/GHSA-r854-jrxh-36qx
- https://github.com/phpseclib/phpseclib/security/advisories/GHSA-r854-jrxh-36qx