lightrag-hku: Stored Cross-Site Scripting (XSS) in the LightRAG WebUI chat/answer renderer via ingested content

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-86062: 0.34% estimated exploitation activity in the next 30 days; percentile 27.27 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The LightRAG WebUI renders assistant/answer chat content as raw HTML — react-markdown is configured with rehypePlugins={[rehypeRaw]} and skipHtml={false} and no HTML sanitizer (rehype-sanitize), element allow-list, or custom urlTransform. Because answer content is derived from user-ingested documents, an attacker who can add a single document can store an HTML/JavaScript payload that executes in the browser of any user who later retrieves it (typically an administrator), leading to auth-token theft from localStorage and full API takeover. No authentication is required in the default configuration. Details Sink — lightragwebui/src/components/retrieval/ChatMessage.tsx: - Main answer (MessageMarkdown, lines ~348-351) and thinking content (lines ~252-272) render with rehypePlugins={[rehypeRaw, …]} and skipHtml={false}. The components map (lines ~111-156) only restyles safe formatting tags (p, h1–h4, ul, ol, li, code); there is no rehype-sanitize, no…

Published by the source

22 Sep 2026, 20:40 UTC

Last modified by the source

1 Oct 2026, 17:55 UTC

Source last checked

26 Oct 2026, 13:54 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-xpjq-3w4w-w5wr

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-xpjq-3w4w-w5wr

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-xpjq-3w4w-w5wr

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# Patch Next advisory brief: CVE-2026-86062

Advisory: lightrag-hku: Stored Cross-Site Scripting (XSS) in the LightRAG WebUI chat/answer renderer via ingested content
IDs: CVE-2026-86062, GHSA-xpjq-3w4w-w5wr
Record: https://patchnext.com/advisories/cve-2026-86062 (revision 3, source checked 26 Oct 2026, 13:54 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: lightrag-hku 1.5.5. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI lightrag-hku: affected <= 1.5.4; fixed in 1.5.5

## Suggested inspection (read-only)
- `python -m pip show lightrag-hku`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on lightrag-hku.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-xpjq-3w4w-w5wr (GitHub-reviewed advisory GHSA-xpjq-3w4w-w5wr lists affected ranges: PyPI lightrag-hku >=0 <=1.5.4)
- Verified: https://osv.dev/vulnerability/GHSA-xpjq-3w4w-w5wr (OSV record GHSA-xpjq-3w4w-w5wr lists affected ranges: PyPI lightrag-hku >=0 <1.5.5 (fixed))

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