USN-8769-1: phpseclib vulnerability
Ubuntu patches phpseclib non-constant-time padding validation enabling remote padding oracle timing attacks against AES-CBC.
Ubuntu security notice USN-8769-1 addresses a vulnerability in phpseclib where padding validation was not performed in constant time when using AES in CBC mode. A remote attacker could leverage this timing side channel to conduct a padding oracle attack and decrypt sensitive information. Users are advised to update the phpseclib package.
- Non-constant-time padding checks in AES-CBC mode expose a timing oracle
- Remote attackers could decrypt sensitive data via padding oracle attack
From the original article
It was discovered that phpseclib did not perform padding validation in constant time when using AES in CBC mode. A remote attacker could possibly use this issue to conduct a padding oracle timing attack and obtain sensitive information.
ubuntu.com
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