Vulnerability in Openid Connect

CVE-2025-27370

OpenID Connect Core through 1.0 errata set 2 allows audience injection in certain situations. When the private_key_jwt authentication mechanism is used, a malicious Authorization Server could trick a Client into writing attacker-controlled values into the audience, including token endpoints or issuer identifiers of other Authorization Servers. The malicious Authorization Server could then use these private key JWTs to impersonate the Client.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 6.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:H/A:N.

EPSS exploit prediction

EPSS: 0.003 (25.8th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 26th percentile — 25.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2025-27370: held from 0.003 to 0.003.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: +0.000

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2025-27370?
CVE-2025-27370 is a medium-severity vulnerability in Openid Connect, classified under Authentication Bypass by Primary Weakness. CVSS score: 6.9/10. Published 2025-03-03.
How severe is CVE-2025-27370?
Medium severity. CVSS v3 base score is 6.9 out of 10.
Is CVE-2025-27370 known to be exploited?
1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.