CVE-2026-32935: phpseclib's AES-CBC unpadding susceptible to padding oracle timing attack

Severity: medium (CVSS 5.9 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-03-20 · updated 2026-06-17
Weakness: CWE-208

Description

phpseclib is a PHP secure communications library. Projects using versions 0.1.1 through 1.0.26, 2.0.0 through 2.0.51, and 3.0.0 through 3.0.49 are vulnerable to a to padding oracle timing attack when using AES in CBC mode. This issue has been fixed in versions 1.0.27, 2.0.52 and 3.0.50.

Affected products

phpseclib: before 1.0.27; from 2.0.0 before 2.0.52; from 3.0.0 before 3.0.50 — fixed in 1.0.27, 2.0.52, 3.0.50
Packagist Phpseclib/Phpseclib: from 3.0.0 before 3.0.50; from 2.0.0 before 2.0.52; from 0.1.1 before 1.0.27; 3.0.0, 3.0.1, 3.0.10, 3.0.11, 3.0.12, 3.0.13 (+122) — fixed in 3.0.50, 2.0.52, 1.0.27

How to fix

Upgrade to a fixed version: phpseclib 1.0.27, 2.0.52, 3.0.50; Packagist Phpseclib/Phpseclib 3.0.50, 2.0.52, 1.0.27. Check the vendor advisory for mitigations.

References

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