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CVE-2026-113728

7.5 · HIGH

Bulwark Webmail is a self-hosted webmail client for Stalwart Mail Server.

Published Oct 20, 2026CWE-918EPSS 0.51%

Overview

CVE-2026-113728 is a high-severity vulnerability. It was published on October 20, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

Bulwark Webmail is a self-hosted webmail client for Stalwart Mail Server. Prior to 1.9.2, the unauthenticated POST /api/fetch-ical endpoint validates a caller-supplied hostname with one DNS lookup and then passes the URL to fetch, which performs a separate lookup for the socket connection. An attacker controlling authoritative DNS can return a public address during validation and then rebind the hostname to a loopback, private, link-local, or cloud metadata address for the connection, causing the server to return up to 10 MB of an internal HTTP or HTTPS response. The same check-then-fetch pattern also existed in authenticated JMAP login and TOTP token-exchange flows. This issue is fixed in version 1.9.2.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/bulwarkmail/webmail/commit/3288589e5248dcc1da769cc578827a9ee1adc941GitHubgithub.com/bulwarkmail/webmail/releases/tag/1.9.2GitHubgithub.com/bulwarkmail/webmail/security/advisories/GHSA-24w9-8r42-8jwm

How CyberStrike helps

Frequently asked questions

What is CVE-2026-113728?

CVE-2026-113728 is a high-severity vulnerability. It was published on October 20, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-113728?

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-113728?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-113728?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-113728 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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