CVE-2025-27773 | SimpleSAMLphp SAML2 library has incorrect signature verification for HTTP-Redirect binding

The SimpleSAMLphp SAML2 library is a PHP library for SAML2 related functionality. Prior to versions 4.17.0 and 5.0.0-alpha.20, there is a signature confusion attack in the HTTPRedirect binding. An attacker with any signed SAMLResponse via the HTTP-Redirect binding can cause the application to accept an unsigned message. Versions 4.17.0 and 5.0.0-alpha.20 contain a fix for the issue.

Published: 2025-03-11 Last update: 2026-04-15 Assigner: [email protected] Source: [email protected]
NVD Status：Deferred，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-27773 is rated Moderate Risk (47.4/100): CVSS High severity, with low exploitation likelihood (EPSS 0.15%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-27773

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-12-26 0.05% 0.15% +0.10%
2 2025-07-11 0.04% 0.05% +0.01%
3 2025-03-12 — 0.04% —

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-27773

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.6 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 4.0 [email protected]

Weakness enumeration for CVE-2025-27773

GitHub Security Advisory for CVE-2025-27773

GHSA-46r4-f8gj-xg56 · Severity: high · Ecosystem: composer — The SimpleSAMLphp SAML2 library incorrectly verifies signatures for HTTP-Redirect binding

OS Trackers for CVE-2025-27773

vendor priority summary link
debian not yet assigned CVE-2025-27773 not yet assigned priority: Debian including 1 source packages (simplesamlphp), 3 status rows across 3 suites (bookworm, bullseye, sid): resolved 3. https://security-tracker.debian.org/tracker/CVE-2025-27773
ubuntu medium CVE-2025-27773 medium priority: Ubuntu including 1 source packages (simplesamlphp), 9 status rows across 9 suites (bionic, focal, jammy, noble, oracular, plucky, questing, upstream, xenial): needs-triage 7, ignored 2. https://ubuntu.com/security/CVE-2025-27773

Affected software / configurations for CVE-2025-27773

Vendor Product Version Raw CPE
No affected products in dataset.

References for CVE-2025-27773

cvelogic Threat Intelligence