What is CVE-2026-55599?

CVE-2026-55599 is a medium-severity vulnerability in Phpseclib, classified under Server-Side Request Forgery (SSRF). CVSS score: 5.8/10. Published 2026-06-22.

How severe is CVE-2026-55599?

Medium severity. CVSS v3 base score is 5.8 out of 10.

SSRF in Phpseclib

CVE-2026-55599

phpseclib is a PHP secure communications library. From 0.1.1 until 1.0.30, 2.0.55, and 3.0.54, when an application validates an untrusted X.509 certificate with phpseclib, X509::validateSignature() reads a URL out of that certificate's Aut…

Vulnerability class: SSRF (Server-Side Request Forgery)

CVSS v3 metric

CVSS v3 base score 5.8 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N.

Affected products

Phpseclib — versions >= 0.1.1, < 1.0.30, >= 2.0.0, < 2.0.55, >= 3.0.0, < 3.0.54

Weakness classification (CWE)

CWE-918 — Server-Side Request Forgery (SSRF)

References

security-advisories@github.com (x_refsource_CONFIRM)

Frequently asked questions

What is CVE-2026-55599?: CVE-2026-55599 is a medium-severity vulnerability in Phpseclib, classified under Server-Side Request Forgery (SSRF). CVSS score: 5.8/10. Published 2026-06-22.
How severe is CVE-2026-55599?: Medium severity. CVSS v3 base score is 5.8 out of 10.