How severe is CVE-2025-27773?

CVE-2025-27773 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2025-27773 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (21st percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2025-27773?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2025-27773 have an EU (EUVD) identifier?

Yes. CVE-2025-27773 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-7804.

When was CVE-2025-27773 published?

CVE-2025-27773 was published on 2025-03-11 and last updated on 2026-06-17.

CVE-2025-27773

CVE-2025-27773 is a high-severity vulnerability with a CVSS 3.x base score of 8.6. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-347.

Key facts

Severity: High (CVSS 3.x base score 8.6)
EPSS exploit prediction: 0% (21st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-7804
Weakness: CWE-347
Published: 2025-03-11
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2025-27773?: 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.
How severe is CVE-2025-27773?: CVE-2025-27773 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2025-27773 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (21st percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2025-27773?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2025-27773 have an EU (EUVD) identifier?: Yes. CVE-2025-27773 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-7804.
When was CVE-2025-27773 published?: CVE-2025-27773 was published on 2025-03-11 and last updated on 2026-06-17.

References

Other CWE-347 (Improper Verification of Cryptographic Signature) vulnerabilities

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CVE-2024-45409 — Critical (CVSS 10.0): The Ruby SAML library is for implementing the client side of a SAML authorization. Ruby-SAML in <= 12.2 and 1.13.0 <=…
CVE-2024-32962 — Critical (CVSS 10.0): xml-crypto is an xml digital signature and encryption library for Node.js. In affected versions the default…
CVE-2022-24884 — Critical (CVSS 10.0): ecdsautils is a tiny collection of programs used for ECDSA (keygen, sign, verify). `ecdsa_verify_[prepare_]legacy()`…
CVE-2021-33885 — Critical (CVSS 10.0): An Insufficient Verification of Data Authenticity vulnerability in B. Braun SpaceCom2 prior to 012U000062 allows a…

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