VulnerabilityDeferred

CVE-2026-55486

The Goobi viewer is a web application that allows digitised material to be displayed in a web browser.

CRITICAL 9.3EPSS 0.26%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.26%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

The Goobi viewer is a web application that allows digitised material to be displayed in a web browser. From version 25.08 to before version 26.05, the IIIF Auth 2.0 endpoints auth/login and auth/token in AuthorizationFlowResource accept an origin query parameter without validation and then (1) embed it into the Content-Security-Policy: frame-ancestors response header and (2) embed it into an HTML response body as a JavaScript single-quoted postMessage argument. Because the attacker controls both the login and token calls that initiate the flow, the unescaped value yields reflected XSS. This issue has been patched in version 26.05.

CVSS 3.1: 9.3 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
EPSS: 0.26% probability · 17th percentile
Public exploits: None in Exploit-DB
CISA KEV: Not listed
Weakness: CWE-79, CWE-113, CWE-1336
Source: security-advisories@github.com

EPSS trend

EPSS moved from 0.5% on 24 October 2026 to 0.3% on 26 October 2026.

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.