# CVE-2026-40194: php-phpseclib: phpseclib is a PHP secure communications library

CVE-2026-40194 is fixed in 3 products on 1 platform, first by DEBIAN-CVE-2026-40194, released April 10, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-40194
- Priority: Routine
- CVSS: 3.7 (low)
- EPSS: 0.0037
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Apr 10, 2026

## Description

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, phpseclib\Net\SSH2::get_binary_packet() uses PHP's != 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | php-phpseclib Debian 12.15 (bookworm) | 2.0.42-1+deb12u4 | [DEBIAN-CVE-2026-40194](https://patchblox.com/security/data/fix/linux/debian-cve-2026-40194.md) | Apr 10, 2026 |
| Linux | php-phpseclib Debian 13.5 (trixie) | 2.0.48-3+deb13u2 | [DEBIAN-CVE-2026-40194](https://patchblox.com/security/data/fix/linux/debian-cve-2026-40194.md) | Apr 10, 2026 |
| Linux | php-phpseclib Debian 14 | 2.0.53-1 | [DEBIAN-CVE-2026-40194](https://patchblox.com/security/data/fix/linux/debian-cve-2026-40194.md) | Apr 10, 2026 |
| Linux | php-phpseclib Ubuntu 18.04.6 LTS (bionic) | 2.0.9-1ubuntu0.1~esm3 | [php-phpseclib 2.0.9-1ubuntu0.1~esm3](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-php-phpseclib-2.0.9-1ubuntu0.1-esm3.md) | May 12, 2026 |
| Linux | php-phpseclib Ubuntu 20.04 LTS (focal) | 2.0.23-2ubuntu0.1~esm3 | [php-phpseclib 2.0.23-2ubuntu0.1~esm3](https://patchblox.com/security/data/fix/linux/ubuntu-focal-php-phpseclib-2.0.23-2ubuntu0.1-esm3.md) | May 12, 2026 |
| Linux | php-phpseclib Ubuntu 22.04.1 LTS (jammy) | 2.0.36-1ubuntu0.1~esm3 | [php-phpseclib 2.0.36-1ubuntu0.1~esm3](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-php-phpseclib-2.0.36-1ubuntu0.1-esm3.md) | May 12, 2026 |
| Linux | php-phpseclib Ubuntu 24.04.5 LTS (noble) | 2.0.47-1ubuntu0.1~esm1 | [php-phpseclib 2.0.47-1ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-php-phpseclib-2.0.47-1ubuntu0.1-esm1.md) | May 12, 2026 |
| Linux | php-phpseclib Ubuntu 26.04.1 LTS (resolute) | 2.0.51-1ubuntu0.1~esm1 | [php-phpseclib 2.0.51-1ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-php-phpseclib-2.0.51-1ubuntu0.1-esm1.md) | May 12, 2026 |
| Linux | php-phpseclib3 Debian 12.15 (bookworm) | 3.0.19-1+deb12u5 | [DEBIAN-CVE-2026-40194](https://patchblox.com/security/data/fix/linux/debian-cve-2026-40194.md) | Apr 10, 2026 |
| Linux | php-phpseclib3 Debian 13.5 (trixie) | 3.0.43-2+deb13u2 | [DEBIAN-CVE-2026-40194](https://patchblox.com/security/data/fix/linux/debian-cve-2026-40194.md) | Apr 10, 2026 |
| Linux | php-phpseclib3 Debian 14 | 3.0.51-1 | [DEBIAN-CVE-2026-40194](https://patchblox.com/security/data/fix/linux/debian-cve-2026-40194.md) | Apr 10, 2026 |
| Linux | phpseclib Debian 12.15 (bookworm) | 1.0.20-1+deb12u4 | [DEBIAN-CVE-2026-40194](https://patchblox.com/security/data/fix/linux/debian-cve-2026-40194.md) | Apr 10, 2026 |
| Linux | phpseclib Debian 13.5 (trixie) | 1.0.23-6+deb13u2 | [DEBIAN-CVE-2026-40194](https://patchblox.com/security/data/fix/linux/debian-cve-2026-40194.md) | Apr 10, 2026 |

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Data as of 2026-11-08T19:12:23Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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