CVE-2026-54025: LibreChat is an enhanced ChatGPT clone that supports multiple AI providers. Prior to 0.8.4-rc1, there is a vulnerability in LibreChat's markdown artif...

Description

LibreChat is an enhanced ChatGPT clone that supports multiple AI providers. Prior to 0.8.4-rc1, there is a vulnerability in LibreChat's markdown artifact preview pipeline. The marked library v15.0.12 does not HTML-escape double-quote characters in image alt text when a custom renderer falls through to the default renderer. LibreChat's generateMarkdownHtml function (in client/src/utils/markdown.ts) installs a custom image renderer that returns false for URLs passing the isSafeUrl allowlist check, which causes marked to fall back to its built-in renderer. That built-in renderer inserts the raw alt text into the alt="..." attribute without escaping double-quote characters. An attacker can craft an alt text such as " onload="payload to break out of the attribute and inject an arbitrary event handler. The resulting HTML is then assigned to document.getElementById('content').innerHTML inside the Sandpack preview iframe, causing the payload to execute in the victim's browser. This vulnerability is fixed in 0.8.4-rc1.

Metrics

CVSS 3.1

5.4/10

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

EPSS Probability

0.13%

3.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-79

References

Timeline

Published: Jun 25, 2026
Last Modified: Jun 25, 2026
Status: Undergoing Analysis

Frequently Asked Questions

What is CVE-2026-54025?

LibreChat is an enhanced ChatGPT clone that supports multiple AI providers. Prior to 0.8.4-rc1, there is a vulnerability in LibreChat's markdown artifact preview pipeline. The marked library v15.0.12 does not HTML-escape double-quote characters in image alt text when a custom renderer falls through to the default renderer. LibreChat's generateMarkdownHtml function (in client/src/utils/markdown.ts) installs a custom image renderer that returns false for URLs passing the isSafeUrl allowlist check, which causes marked to fall back to its built-in renderer. That built-in renderer inserts the raw alt text into the alt="..." attribute without escaping double-quote characters. An attacker can craft an alt text such as " onload="payload to break out of the attribute and inject an arbitrary event handler. The resulting HTML is then assigned to document.getElementById('content').innerHTML inside the Sandpack preview iframe, causing the payload to execute in the victim's browser. This vulnerability is fixed in 0.8.4-rc1.

How severe is CVE-2026-54025?

CVE-2026-54025 has a CVSS score of 5.4/10 (MEDIUM severity). The EPSS model estimates a 0.13% probability of exploitation in the next 30 days.

How do I fix CVE-2026-54025?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.