CVE-2026-40014
published 2026-08-28CVE-2026-40014: 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…
PriorityP431medium6.5CVSS 3.1
AVNACLPRNUIRSUCNINAH
EPSS
0.33%
25.6th percentile
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.
Affected
5 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| dovecot | dovecot | — | — |
| open-xchange_gmbh | ox_dovecot_ce | >= 2.3.0 < 2.4.5 | 2.4.5 |
| open-xchange_gmbh | ox_dovecot_pro | >= 2.3.0 < 2.3.22.2 | 2.3.22.2 |
| open-xchange_gmbh | ox_dovecot_pro | >= 3.0.0 < 3.0.7 | 3.0.7 |
| open-xchange_gmbh | ox_dovecot_pro | >= 3.1.0 < 3.1.6 | 3.1.6 |
CVSS provenance
nvdv3.16.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
vendor_redhat6.5MEDIUM
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GHSA
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.
ghsa_unreviewed·2026-08-28
CVE-2026-40014 [MEDIUM] CWE-400 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.
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.
GHSA
An attacker that can send mail to a user can craft a message header whose values are chosen to collide in an internal hash table, which makes the IMAP THREAD command consume CPU disproportionate to th
ghsa_unreviewed·2026-08-28·CVSS 6.5
CVE-2026-40017 [MEDIUM] CWE-400 An attacker that can send mail to a user can craft a message header whose values are chosen to collide in an internal hash table, which makes the IMAP THREAD command consume CPU disproportionate to th
An attacker that can send mail to a user can craft a message header whose values are chosen to collide in an internal hash table, which makes the IMAP THREAD command consume CPU disproportionate to the size of the message. This is a separate issue from CVE-2026-40014 and is not addressed by that fix. Whenever 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.
Red Hat
dovecot: Dovecot: Denial of Service via crafted IMAP message headers
vendor_redhat·2026-08-28·CVSS 6.5
CVE-2026-40017 [MEDIUM] CWE-770 dovecot: Dovecot: Denial of Service via crafted IMAP message headers
dovecot: Dovecot: Denial of Service via crafted IMAP message headers
An attacker that can send mail to a user can craft a message header whose values are chosen to collide in an internal hash table, which makes the IMAP THREAD command consume CPU disproportionate to the size of the message. This is a separate issue from CVE-2026-40014 and is not addressed by that fix. Whenever 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.
A flaw was found in Dovecot. A remote attacker who can send mail to a user can craft a message
Red Hat
dovecot: Dovecot: Denial of Service via crafted IMAP THREAD command
vendor_redhat·2026-08-28·CVSS 6.5
CVE-2026-40014 [MEDIUM] CWE-606 dovecot: Dovecot: Denial of Service via crafted IMAP THREAD command
dovecot: Dovecot: Denial of Service via crafted IMAP THREAD command
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.
A flaw was found in Dovecot. A remote attacker, by sending a specially crafted email message header to a user, can cause the Internet Message Access Protocol (IMAP) THREAD command to consume excessive CPU resources. When a mail client process
No detection rules found.
No public exploits indexed.
Bugzilla
CVE-2026-40017 dovecot: Dovecot: Denial of Service via crafted IMAP message headers [fedora-all]
bugzilla·2026-09-01·CVSS 6.5
CVE-2026-40017 [MEDIUM] CVE-2026-40017 dovecot: Dovecot: Denial of Service via crafted IMAP message headers [fedora-all]
CVE-2026-40017 dovecot: Dovecot: Denial of Service via crafted IMAP message headers [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
An attacker that can send mail to a user can craft a message header whose values are chosen to collide in an internal hash table, which makes the IMAP THREAD command consume CPU disproportionate to the size of the message. This is a separate issue from CVE-2026-40014 and is not addressed by that fix. Whenever 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 t
Bugzilla
CVE-2026-40014 dovecot: Dovecot: Denial of Service via crafted IMAP THREAD command [fedora-all]
bugzilla·2026-09-01·CVSS 6.5
CVE-2026-40014 [MEDIUM] CVE-2026-40014 dovecot: Dovecot: Denial of Service via crafted IMAP THREAD command [fedora-all]
CVE-2026-40014 dovecot: Dovecot: Denial of Service via crafted IMAP THREAD command [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
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 a
Bugzilla
CVE-2026-40017 dovecot: Dovecot: Denial of Service via crafted IMAP message headers
bugzilla·2026-08-28·CVSS 6.5
CVE-2026-40017 [MEDIUM] CVE-2026-40017 dovecot: Dovecot: Denial of Service via crafted IMAP message headers
CVE-2026-40017 dovecot: Dovecot: Denial of Service via crafted IMAP message headers
An attacker that can send mail to a user can craft a message header whose values are chosen to collide in an internal hash table, which makes the IMAP THREAD command consume CPU disproportionate to the size of the message. This is a separate issue from CVE-2026-40014 and is not addressed by that fix. Whenever 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.
Bugzilla
CVE-2026-40014 dovecot: Dovecot: Denial of Service via crafted IMAP THREAD command
bugzilla·2026-08-28·CVSS 6.5
CVE-2026-40014 [MEDIUM] CVE-2026-40014 dovecot: Dovecot: Denial of Service via crafted IMAP THREAD command
CVE-2026-40014 dovecot: Dovecot: Denial of Service via crafted IMAP THREAD command
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.
2026-08-28
Published