Reference page — cumulative record through Wednesday, August 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.
phpseclib: X.509 certificate validation sends attacker-controlled outbound requests (server-side request forgery) via Authority Information Access
AV AC PR UI S C I A CVSS EPSS %ile KEV
N L N N C L N N 5.8 .0016 5.2 —
AFFECTED
Product Versions Fixed
phpseclib >= 0.1.1, < 1.0.30 – —
TIMELINE
Jun 16 Reserved by GitHub_M
Jun 22 EXPLOIT PUBLISHED — CVE-2026-55599 (phpseclib). Public exploit reference added.
Jun 22 Published (CNA: GitHub_M)
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.
Lifecycle
Complete event history — 3 events, chronological
| Date | Event | Detail |
|---|
| June 16, 2026 | Reserved | Reserved by GitHub_M |
| June 22, 2026 | EXPLOIT PUBLISHED | EXPLOIT PUBLISHED — CVE-2026-55599 (phpseclib). Public exploit reference added. |
| June 22, 2026 | Published | Published (CNA: GitHub_M) |
Affected
Affected products and packages — 1 row
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
|---|
| phpseclib | phpseclib | — | >= 0.1.1, < 1.0.30 | — |
About this page
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-55599 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Wednesday, August 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.