USN-8830-1: phpseclib vulnerabilities

Publication date

28 September 2026

Overview

Several security issues were fixed in phpseclib.


Packages

  • php-phpseclib - implementations of an arbitrary-precision integer arithmetic library

Details

It was discovered that phpseclib did not perform constant-time padding
validation when using AES in CBC mode. A remote attacker could possibly
use this issue to obtain sensitive information. (CVE-2026-32935)

It was discovered that phpseclib did not use a constant-time comparison
when validating SSH packet authentication codes. A remote attacker could
possibly use this issue to obtain sensitive information. (CVE-2026-40194)

It was discovered that phpseclib did not properly limit object identifier
lengths when parsing ASN.1 data. An attacker could possibly use this issue
to cause phpseclib to use excessive resources, leading to a denial of
service. (CVE-2026-44167)

It was discovered that phpseclib did not perform constant-time padding
validation when using AES in CBC mode. A remote attacker could possibly
use this issue to obtain sensitive information. (CVE-2026-32935)

It was discovered that phpseclib did not use a constant-time comparison
when validating SSH packet authentication codes. A remote attacker could
possibly use this issue to obtain sensitive information. (CVE-2026-40194)

It was discovered that phpseclib did not properly limit object identifier
lengths when parsing ASN.1 data. An attacker could possibly use this issue
to cause phpseclib to use excessive resources, leading to a denial of
service. (CVE-2026-44167)

Update instructions

In general, a standard system update will make all the necessary changes.

Learn more about how to get the fixes.

The problem can be corrected by updating your system to the following package versions:

Ubuntu Release Package Version
26.04 LTS resolute php-phpseclib –  2.0.51-1ubuntu0.1~esm1  
24.04 LTS noble php-phpseclib –  2.0.47-1ubuntu0.1~esm1  
22.04 LTS jammy php-phpseclib –  2.0.36-1ubuntu0.1~esm3  
20.04 LTS focal php-phpseclib –  2.0.23-2ubuntu0.1~esm3  
18.04 LTS bionic php-phpseclib –  2.0.9-1ubuntu0.1~esm3  
16.04 LTS xenial php-phpseclib –  2.0.1-1ubuntu0.1~esm1

Reduce your security exposure

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