CVE-2024-23184

Dovecot is an IMAP server for Linux/UNIX-like systemsa wrapper package that will just handle common things for all versioned dovecot packages.

Security Fix(es):

(CVE-2024-23184)

(CVE-2024-23185)

Having a large number of address headers (From, To, Cc, Bcc, etc.) becomes excessively CPU intensive. With 100k header lines CPU usage is already 12 seconds, and in a production environment we observed 500k header lines taking 18 minutes to parse. Since this can be triggered by external actors sending emails to a victim, this is a security issue. An external attacker can send specially crafted messages that consume target system resources and cause outage. One can implement restrictions on address headers on MTA component preceding Dovecot. No publicly available exploits are known.

Dovecot is an IMAP server for Linux and other UNIX-like systems, written primarily with security in mind. It also contains a small POP3 server, and supports e-mail in either the maildir or mbox format. The SQL drivers and authentication plug-ins are provided as subpackages.

Security Fix(es):

• dovecot: using a large number of address headers may trigger a denial of service (CVE-2024-23184)
• dovecot: very large headers can cause resource exhaustion when parsing message (CVE-2024-23185)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Dovecot is an IMAP server for Linux and other UNIX-like systems, written primarily with security in mind. It also contains a small POP3 server, and supports e-mail in either the maildir or mbox format. The SQL drivers and authentication plug-ins are provided as subpackages.

Security Fix(es):

• dovecot: using a large number of address headers may trigger a denial of service (CVE-2024-23184)
• dovecot: very large headers can cause resource exhaustion when parsing message (CVE-2024-23185)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Having a large number of address headers (From, To, Cc, Bcc, etc.) becomes excessively CPU intensive. With 100k header lines CPU usage is already 12 seconds, and in a production environment we observed 500k header lines taking 18 minutes to parse. Since this can be triggered by external actors sending emails to a victim, this is a security issue. An external attacker can send specially crafted messages that consume target system resources and cause outage. One can implement restrictions on address headers on MTA component preceding Dovecot. No publicly available exploits are known.

Having a large number of address headers (From, To, Cc, Bcc, etc.) becomes excessively CPU intensive. With 100k header lines CPU usage is already 12 seconds, and in a production environment we observed 500k header lines taking 18 minutes to parse. Since this can be triggered by external actors sending emails to a victim, this is a security issue. An external attacker can send specially crafted messages that consume target system resources and cause outage. One can implement restrictions on address headers on MTA component preceding Dovecot. No publicly available exploits are known.

• CVE-2024-23184: restrict address headers to mitigate excessive CPU usage and prevent potential DoS attacks

Having a large number of address headers (From, To, Cc, Bcc, etc.) becomes excessively CPU intensive. With 100k header lines CPU usage is already 12 seconds, and in a production environment we observed 500k header lines taking 18 minutes to parse. Since this can be triggered by external actors sending emails to a victim, this is a security issue. An external attacker can send specially crafted messages that consume target system resources and cause outage. One can implement restrictions on address headers on MTA component preceding Dovecot. No publicly available exploits are known.

CVE-2024-23184: A large number of address headers in email resulted in excessive CPU usage. CVE-2024-23185: Abnormally large email headers are now truncated or discarded, with a limit of 10MB on a single header and 50MB for all the headers of all the parts of an email.

These are all security issues fixed in the dovecot23-2.3.21.1-1.1 package on the GA media of openSUSE Tumbleweed.

These are all security issues fixed in the dovecot24-2.4.0-1.1 package on the GA media of openSUSE Tumbleweed.

Dovecot is an IMAP server for Linux and other UNIX-like systems, written primarily with security in mind. It also contains a small POP3 server, and supports e-mail in either the maildir or mbox format. The SQL drivers and authentication plug-ins are provided as subpackages.

Security Fix(es):

• dovecot: using a large number of address headers may trigger a denial of service (CVE-2024-23184)

• dovecot: very large headers can cause resource exhaustion when parsing message (CVE-2024-23185)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Dovecot is an IMAP server for Linux and other UNIX-like systems, written primarily with security in mind. It also contains a small POP3 server, and supports e-mail in either the maildir or mbox format. The SQL drivers and authentication plug-ins are provided as subpackages.

Security Fix(es):

• dovecot: using a large number of address headers may trigger a denial of service (CVE-2024-23184)

• dovecot: very large headers can cause resource exhaustion when parsing message (CVE-2024-23185)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

This update for dovecot23 fixes the following issues:

• CVE-2024-23185: Fixed a denial of service with large headers (bsc#1229183)
• CVE-2024-23184: Fixed a denial of service parsing messages containing many address headers (bsc#1229184)

This update for dovecot23 fixes the following issues:

• CVE-2024-23184: parsing of messages containing many address headers (From, To, Cc, Bcc, etc.) could be excessively CPU intensive (bsc#1229184).
• CVE-2024-23185: large headers can cause resource exhaustion when parsing message (bsc#1229183).
• CVE-2025-59028: Invalid base64 authentication can cause DoS for other logins (bsc#1260894).
• CVE-2025-59031: decode2text.sh OOXML extraction may follow symlinks and read unintended files during indexing (bsc#1260895).
• CVE-2025-59032: pigeonhole: ManageSieve panic occurs with sieve-connect as a client (bsc#1260902).
• CVE-2026-27852: DoS by sending mail with bad header (bsc#1276799).
• CVE-2026-27855: OTP driver vulnerable to replay attack (bsc#1260900).
• CVE-2026-27856: Doveadm credentials were not checked using timing-safe checking function (bsc#1260899).
• CVE-2026-27857: sending excessive parenthesis causes imap-login to use excessive memory (bsc#1260898).
• CVE-2026-27858: pigeonhole: managesieve-login can allocate large amount of memory during authentication (bsc#1260901).
• CVE-2026-27859: excessive RFC 2231 MIME parameters in email would can excessive CPU usage (bsc#1260897).
• CVE-2026-33263: submission-login: Panic when mail_max_userip_connections is reached (bsc#1276794).
• CVE-2026-33603: login: base64 input can contain tabs that bypass IPC protection (bsc#1265147).
• CVE-2026-33604: SMTP Smuggling via Missing Dot-Stuffing (bsc#1276802).
• CVE-2026-33605: managesieve-login: Pre-auth crash (bsc#1276809).
• CVE-2026-33606: dsync: Mail content can cause dsync protocol injection (bsc#1276800).
• CVE-2026-33607: IMAP LIST match_sub() Exponential Backtracking -- CPU Denial of Service (bsc#1276795).
• CVE-2026-40014: CPU DoS via Crafted References Header (bsc#1276804).
• CVE-2026-40015: imap-hibernate can be crashed (bsc#1276812).
• CVE-2026-40016: Sieve :contains/:matches O(NxM) substring match bypasses sieve_max_cpu_time limit (bsc#1265148).
• CVE-2026-40019: managesieve-login pre-auth infinite loop (bsc#1276811).
• CVE-2026-40020: IMAP folders can be shared-spammed to everyone (bsc#1265149).
• CVE-2026-40203: IMAP Compression Can Reveal Whether a Small Synced Email Body Matches Sender-Chosen Text (bsc#1276815).
• CVE-2026-40205: OAuth2 passdb scope enforcement bypass via OR semantics in remote validation path (bsc#1276820).
• CVE-2026-42006: imap-login: uncontrolled memory usage with excessive bracing over IMAP (bsc#1265150).
• CVE-2026-42007: editheader RCE (bsc#1276817).
• CVE-2026-42008: XCLIENT FORWARD= bare token not namespaced (bsc#1276824).
• CVE-2026-42391: imap: Pre-login memory/CPU growth with ID command (bsc#1276835).
• CVE-2026-42393: doveadm_password or api key length can still be leaked with timing comparisons (bsc#1276827).
• CVE-2026-42395: Single NUL-Byte XCLIENT FORWARD Payload Crashes (bsc#1276826).
• CVE-2026-52681: Sieve resource usage tracking lost when active script changes (bsc#1276828).
• CVE-2026-52687: IMAP: COMPRESS ZSTD can cause excessive memory usage (bsc#1276837).
• CVE-2026-73208: auth: db-oauth2: aud claim used as fallback for missing scope claim (bsc#1276830).
• CVE-2026-73209: imap-login crash: Self-recursion on zero-output decompress chunks (bsc#1276833).

Changes for dovecot23:

• Update to version 2.3.21.1.

It was discovered that Dovecot did not not properly have restrictions on ithe size of address headers. A remote attacker could possibly use this issue to cause denial of service. (CVE-2024-23184, CVE-2024-23185)

It was discovered that Dovecot incorrectly handled a large number of address headers. A remote attacker could possibly use this issue to cause Dovecot to consume resources, leading to a denial of service. (CVE-2024-23184)

It was discovered that Dovecot incorrectly handled very large headers. A remote attacker could possibly use this issue to cause Dovecot to consume resources, leading to a denial of service. (CVE-2024-23185)