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CVE-2026-55599

24
FAUCET Score

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.

First published: Jun 22, 2026Last modified: Jun 22, 2026

Impacted Technologies

VendorProductVersion(s)CPE
>= 0.1.1, < 1.0.30CPE matchmatch criteria
cpe:2.3:a:phpseclib:phpseclib:*:*:*:*:*:*:*:*
>= 2.0.0, < 2.0.55CPE matchmatch criteria
cpe:2.3:a:phpseclib:phpseclib:*:*:*:*:*:*:*:*
>= 3.0.0, < 3.0.54CPE matchmatch criteria
cpe:2.3:a:phpseclib:phpseclib:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.8MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
LOW
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.16%
Probability of exploitation in next 30 days
EPSS Percentile
5.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0016 is in the 1st percentile among its peer group of 23,705 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (3)

composerpatch availablevia ghsa
Product: phpseclib/phpseclibFixed in: 1.0.30
composerpatch availablevia ghsa
Product: phpseclib/phpseclibFixed in: 2.0.55
composerpatch availablevia ghsa
Product: phpseclib/phpseclibFixed in: 3.0.54

Vendor Advisories (1)

composerGHSA-m557-wrgg-6rp4medium

phpseclib: X.509 certificate validation sends attacker-controlled outbound requests (server-side request forgery) via Authority Information Access

Jun 16, 2026

References

github.com / phpseclib/phpseclib/security/advisories/GHSA-m557-wrgg-6rp4
ExploitMitigationVendor Advisory