CVE-2026-55486: XSS (CVSS 9.3)

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.

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CVSS v3.1 Score

9.3

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N

EPSS — Exploit Prediction

0.0026

Probability of exploitation

0.17%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-79 Cross-site Scripting (XSS)

CWE-113 CWE-113

CWE-1336 CWE-1336

References

Other References

https://github.com/intranda/goobi-viewer-core/commit/0e488c6b02a28c1d1a747dfe3958ad2bbcff2d0b https://github.com/intranda/goobi-viewer-core/releases/tag/v26.05 https://github.com/intranda/goobi-viewer-core/security/advisories/GHSA-975w-g9gj-xq48

Frequently Asked Questions

What is CVE-2026-55486? +

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. It has a CVSS v3.1 base score of 9.3 (CRITICAL).

How severe is CVE-2026-55486? +

CVE-2026-55486 has a CVSS v3.1 score of 9.3 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0026, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-55486? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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