Vulnerability Description
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 Authority Information Access (AIA) extension and connects to it. Attacker who supplies certificate fully controls host, port, and path of that connection. URL fetching is enabled by default, and no destination is blocked. An unauthenticated attacker can therefore make a validating server open connections to internal hosts and ports it should never reach, for example loopback 127.0.0.1, cloud metadata address 169.254.169.254, and internal-only services. This is a server-side request forgery (SSRF) caused by an insecure default. This vulnerability is fixed in 1.0.30, 2.0.55, and 3.0.54.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Phpseclib | Phpseclib | >= 0.1.1, < 1.0.30 |
Related Weaknesses (CWE)
References
- https://github.com/phpseclib/phpseclib/security/advisories/GHSA-m557-wrgg-6rp4ExploitMitigationVendor Advisory
- https://github.com/phpseclib/phpseclib/security/advisories/GHSA-m557-wrgg-6rp4ExploitMitigationVendor Advisory
FAQ
What is CVE-2026-55599?
CVE-2026-55599 is a vulnerability with a CVSS score of 5.8 (MEDIUM). 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() re...
How severe is CVE-2026-55599?
CVE-2026-55599 has been rated MEDIUM with a CVSS base score of 5.8/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-55599?
Check the references section above for vendor advisories and patch information. Affected products include: Phpseclib Phpseclib.