What is CVE-2026-35391?

CVE-2026-35391 is a high-severity vulnerability in Bulwarkmail Webmail, classified under CWE-348. CVSS score: 7.5/10. Published 2026-04-06.

How severe is CVE-2026-35391?

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

Vulnerability in Bulwarkmail Webmail

CVE-2026-35391

Bulwark Webmail is a self-hosted webmail client for Stalwart Mail Server. Prior to 1.4.11, the getClientIP() function in lib/admin/session.ts trusted the first (leftmost) entry of the X-Forwarded-For header, which is fully controlled by the client. An attacker could forge their source IP address to bypass IP-based rate limiting (enabling brute-force attacks against the admin login) or forge audit log entries (making malicious activity appear to originate from arbitrary IP addresses). This vulnerability is fixed in 1.4.11.

EPSS: 0.001 (3.3th percentile) — read the EPSS interpretation.

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.

Affected products

Bulwarkmail Webmail — versions < 1.4.11

Weakness classification (CWE)

CWE-348

References

security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)

Frequently asked questions

What is CVE-2026-35391?: CVE-2026-35391 is a high-severity vulnerability in Bulwarkmail Webmail, classified under CWE-348. CVSS score: 7.5/10. Published 2026-04-06.
How severe is CVE-2026-35391?: High severity. CVSS v3 base score is 7.5 out of 10.