Timing Attack Affecting phpseclib/phpseclib package, versions <3.0.57>=4.0.0, <4.0.1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
Do your applications use this vulnerable package?
In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.
Test your applications- Snyk IDSNYK-PHP-PHPSECLIBPHPSECLIB-19666129
- published10 Sept 2026
- disclosed1 Sept 2026
- creditgeostergiop
Introduced: 1 Sep 2026
NewCVE-2026-84308 (opens in a new tab)How to fix?
Upgrade phpseclib/phpseclib to version 3.0.57, 4.0.1 or higher.
Overview
phpseclib/phpseclib is a PHP Secure Communications Library - Pure-PHP implementations of RSA, AES, SSH2, SFTP, X.509 etc.
Affected versions of this package are vulnerable to Timing Attack the pure-PHP X25519 scalar multiplication in Crypt/EC/Formats/Keys/MontgomeryPrivate.php, Crypt/EC/Formats/Keys/PKCS8.php, and Math/PrimeField/Integer.php. An attacker can recover the long-lived X25519 private scalar by measuring per-ladder-step execution time or counting GMP calls while the code multiplies the base point during Montgomery key derivation. The leak comes from data-dependent conditional modular reduction in PrimeField\Integer::add() and subtract(), which makes each ladder step’s cost depend on secret-scalar-dependent field values. In deployments that use phpseclib’s pure-PHP Curve25519 path, this exposes the private key used for ECDH and compromises any shared secret derived from it.