PatchTheCVECVE-2011-1926: The STARTTLS implementation in Cyrus IMAP Server before 2.4.7 does not properly restrict I/O buffering, which
CVE-2011-1926 is a medium-severity flaw (CVSS 5.1) affecting cyrus imap server. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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.
Why this priority
- EPSS top 9%: very likely to be exploited
A fixed release or distro patch exists.
Risk facts
| CVSS score | 5.1 (Medium) |
| EPSS exploit chance | 4.0% (top 9%) |
| CISA exploited list | No |
| Weakness | CWE-264 |
| Published | 2011-05-23 |
| Last modified | 2026-06-16 |
Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2011-1926?
cyrus imap server: upgrade to newer than 2.4.6. Exact commands for each OS are on this page.
Is CVE-2011-1926 being exploited?
CVE-2011-1926 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2011-1926 affect?
CVE-2011-1926 affects cyrus imap server. Severity is medium (CVSS 5.1). 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 aft
How urgent is CVE-2011-1926?
Priority 40/100. EPSS top 9%: very likely to be exploited
Related CVEs
- CVE-2011-3481 MEDIUM 4.3 UPGRADE The index_get_ids function in index.c in imapd in Cyrus IMAP Server before 2.4.11, when server-side threading
- CVE-2011-3208 HIGH 7.5 UPGRADE Stack-based buffer overflow in the split_wildmats function in nntpd.c in nntpd in Cyrus IMAP Server before 2.3
- CVE-2009-2632 MEDIUM 4.4 DOWNGRADE Buffer overflow in the SIEVE script component (sieve/script.c), as used in cyrus-imapd in Cyrus IMAP Server 2.
- CVE-2004-1067 HIGH 10.0 DOWNGRADE MITIGATE Off-by-one error in the mysasl_canon_user function in Cyrus IMAP Server 2.2.9 and earlier leads to a buffer ov
- CVE-2004-1015 HIGH 10.0 DOWNGRADE MITIGATE Buffer overflow in proxyd for Cyrus IMAP Server 2.2.9 and earlier, with the imapmagicplus option enabled, may