What is CVE-2026-34834?

CVE-2026-34834 is a high-severity vulnerability in Bulwarkmail Webmail, classified under Improper Authentication. CVSS score: 7.5/10. Published 2026-04-02.

How severe is CVE-2026-34834?

High severity. CVSS v3 base score is 7.5 out of 10.

Auth bypass in Bulwarkmail Webmail

CVE-2026-34834

Bulwark Webmail is a self-hosted webmail client for Stalwart Mail Server. Prior to version 1.4.10, the verifyIdentity() function contained logic that returned true if no session cookies were present. This allowed unauthenticated attackers to bypass security checks and access/modify user settings via the /api/settings endpoint by providing arbitrary headers. This issue has been patched in version 1.4.10.

Vulnerability class: Broken Authentication

Published 2026-04-02 · last modified 2026-07-24.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.

EPSS exploit prediction

EPSS: 0.004 (34.3th percentile), scored 2026-10-01.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 34th percentile — 34.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.002

Affected products

Bulwarkmail Webmail — versions < 1.4.10

Weakness classification (CWE)

CWE-287 — Improper Authentication

References

github.com/bulwarkmail/webmail/security/advisories/GHSA-4356-876g-rfmh (Vendor Advisory)
github.com/bulwarkmail/webmail/releases/tag/1.4.10 (Product)

Frequently asked questions

What is CVE-2026-34834?: CVE-2026-34834 is a high-severity vulnerability in Bulwarkmail Webmail, classified under Improper Authentication. CVSS score: 7.5/10. Published 2026-04-02.
How severe is CVE-2026-34834?: High severity. CVSS v3 base score is 7.5 out of 10.