| Name | CVE-2026-40014 |
| Description | An attacker that can send mail to a user can craft a message header that makes the IMAP THREAD command consume CPU disproportionate to the size of the message. When a mail client issues a THREAD command on the affected mailbox, this can cause degradation or denial of service for IMAP. Monitor system for abnormal CPU usage, kill the offending process and remove the offending message from the affected mailbox. Update to non-vulnerable version. No publicly available exploits are known. |
| Source | CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
| References | DSA-6526-1 |
| Debian Bugs | 1146018 |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| dovecot (PTS) | bookworm, bookworm (security) | 1:2.3.19.1+dfsg1-2.1+deb12u6 | vulnerable |
| trixie | 1:2.4.1+dfsg1-6+deb13u6 | vulnerable | |
| trixie (security) | 1:2.4.1+dfsg1-6+deb13u7 | fixed | |
| forky | 1:2.4.5+dfsg1-2 | fixed | |
| sid | 1:2.4.5+dfsg1-3 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| dovecot | source | trixie | 1:2.4.1+dfsg1-6+deb13u7 | DSA-6526-1 | ||
| dovecot | source | (unstable) | 1:2.4.5+dfsg1-1 | 1146018 |
https://documentation.open-xchange.com/dovecot/security/advisories/html/2026/oxdc-adv-2026-0003.html#cve-2026-40014-imap-thread-references-o-n2-cpu-dos-via-crafted-references-header-index-thread-links-c
Fixed by: https://github.com/dovecot/core/commit/113eac6cbbae1bf292e7dd1826eede3f929fe6c9
Fixed by: https://github.com/dovecot/core/commit/ad92d716328c646e4dcd4dd2aaa14bc3e422eb8d
Fixed by: https://github.com/dovecot/core/commit/f4e7474bdb5e7557ea3d985f9f27ef8d7f91ad68