CVE-2026-55459

HIGH 7.4

Published 2026-10-23 · Last modified 2026-10-23

The Goobi viewer is a web application that allows digitised material to be displayed in a web browser. From version 25.01 to before version 26.05, AuthenticationEndpoint.verifyOpenIdToken builds its verifier as JWT.require(algorithm).withIssuer(issuer).build() and does not enforce the aud claim during cryptographic validation. The aud check is performed manually afterwards via a single string-equality call, which only handles single-string aud values. In a multi-RP IdP setup, a token whose single-string aud matches the viewer's client ID but was issued for a different relying party passes the check and authenticates the attacker as the token's sub. This issue has been patched in version 26.05.

ELEVATED IMPACT

Severe if exploited (CVSS 7.4), but no known exploitation and low modeled probability. Patch on a normal cadence.

Exploitation likelihood

0.2%chance of exploitation in 30 days · 10th percentile

○ In CISA KEV ○ Catalogued PoC

Impact if exploited

7.4CVSS 3.1 · HIGH

ConfidentialityHigh
IntegrityHigh
AvailabilityNone

What an attacker needs

✓Access: Reachable over the network — no local access needed
✓Privileges: No account or privileges required
✓User interaction: No user interaction needed
⚠Complexity: Needs a race window or specific setup

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept

No public PoC is currently catalogued.

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Data snapshot: 2026-10-26T13:52:32.101Z