What is CVE-2026-121627?

CVE-2026-121627 is a medium-severity vulnerability in Jarun Buku, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-11-03.

How severe is CVE-2026-121627?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Jarun Buku

CVE-2026-121627

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.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2026-11-03.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Jarun Buku

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

github.com/jarun/buku/issues/911 (issue-tracking)
github.com/jarun/buku/blob/v5.1.1/bukuserver/views.py (technical-description)
github.com/jarun/buku (product)
www.vulncheck.com/advisories/buku-5.0-through-5.1.1-stored-xss-via-bukuserver-b… (third-party-advisory)

Frequently asked questions

What is CVE-2026-121627?: CVE-2026-121627 is a medium-severity vulnerability in Jarun Buku, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-11-03.
How severe is CVE-2026-121627?: Medium severity. CVSS v3 base score is 6.1 out of 10.