CVE-2026-27858

dovecot23: This update for dovecot23 fixes the following issues: - CVE-2024-23184: parsing of messages containing many address...

CVE-2026-27858 is fixed in 26 products on 1 platform, first by RHSA-2026:17602, released March 27, 2026. It is not reported as exploited. Patch Radar priority: High.

High
CVSS
7.5
high
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0080
56th percentile

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.

Where it's fixed

ProductFixed inFixReleased
Linux
dovecot · Debian 12.15 (bookworm) 1:2.3.19.1+dfsg1-2.1+deb12u2 DEBIAN-CVE-2026-27858 Mar 27, 2026
dovecot · Debian 13.5 (trixie) 1:2.4.1+dfsg1-6+deb13u4 DEBIAN-CVE-2026-27858 Mar 27, 2026
dovecot · Debian 14 1:2.4.3+dfsg1-1 DEBIAN-CVE-2026-27858 Mar 27, 2026
dovecot · RHEL 10 2.3.21-16.el10_0.1 RHSA-2026:17602 Mar 27, 2026
dovecot · RHEL 8 1:2.3.16-7.el8_10 RHSA-2026:13830 May 15, 2026
dovecot · RHEL 9 1:2.3.16-18.el9_8 RHSA-2026:19364 May 15, 2026
dovecot · almalinux 10 1:2.3.21-19.el10_2 ALSA-2026:19149 May 19, 2026
dovecot · almalinux 8 1:2.3.16-7.el8_10 ALSA-2026:13830 May 5, 2026
dovecot · almalinux 9 1:2.3.16-18.el9_8 ALSA-2026:19364 May 19, 2026
dovecot · amzn 2023 1:2.3.20-1.amzn2023.0.3 ALAS2023-2026-1570 Apr 13, 2026
dovecot · ol 10 1:2.3.21-16.el10_1.1 ELSA-2026-13498 May 5, 2026
dovecot · ol 8 1:2.3.16-7.el8_10 ELSA-2026-13830 May 6, 2026
dovecot · ol 9 1:2.3.16-15.el9_7.1 ELSA-2026-13857 May 6, 2026
dovecot · rocky 10 1:2.3.21-19.el10_2 RLSA-2026:19149 May 29, 2026
dovecot · rocky 8 1:2.3.16-7.el8_10 RLSA-2026:13830 May 7, 2026
dovecot · rocky 9 1:2.3.16-18.el9_8 RLSA-2026:19364 May 28, 2026
dovecot-auth-lua · Ubuntu 22.04.1 LTS (jammy) 1:2.3.16+dfsg1-3ubuntu2.7 dovecot-auth-lua 1:2.3.16+dfsg1-3ubuntu2.7 Apr 15, 2026
dovecot-auth-lua · Ubuntu 24.04.5 LTS (noble) 1:2.3.21+dfsg1-2ubuntu6.3 dovecot-auth-lua 1:2.3.21+dfsg1-2ubuntu6.3 Apr 15, 2026
dovecot-auth-lua · Ubuntu 25.10 (questing) 1:2.4.1+dfsg1-5ubuntu4.1 dovecot-auth-lua 1:2.4.1+dfsg1-5ubuntu4.1 Apr 15, 2026
dovecot-core · Ubuntu 22.04.1 LTS (jammy) 1:2.3.16+dfsg1-3ubuntu2.7 dovecot-core 1:2.3.16+dfsg1-3ubuntu2.7 Apr 15, 2026
dovecot-core · Ubuntu 24.04.5 LTS (noble) 1:2.3.21+dfsg1-2ubuntu6.3 dovecot-core 1:2.3.21+dfsg1-2ubuntu6.3 Apr 15, 2026
dovecot-core · Ubuntu 25.10 (questing) 1:2.4.1+dfsg1-5ubuntu4.1 dovecot-core 1:2.4.1+dfsg1-5ubuntu4.1 Apr 15, 2026
dovecot-debuginfo · amzn 2023 1:2.3.20-1.amzn2023.0.3 ALAS2023-2026-1570 Apr 13, 2026
dovecot-debugsource · amzn 2023 1:2.3.20-1.amzn2023.0.3 ALAS2023-2026-1570 Apr 13, 2026
dovecot-devel · RHEL 8 1:2.3.16-7.el8_10 RHSA-2026:13830 May 15, 2026
dovecot-devel · RHEL 9 1:2.3.16-18.el9_8 RHSA-2026:19364 May 15, 2026
dovecot-devel · almalinux 10 1:2.3.21-19.el10_2 ALSA-2026:19149 May 19, 2026
dovecot-devel · almalinux 8 1:2.3.16-7.el8_10 ALSA-2026:13830 May 5, 2026
dovecot-devel · almalinux 9 1:2.3.16-18.el9_8 ALSA-2026:19364 May 19, 2026
dovecot-devel · amzn 2023 1:2.3.20-1.amzn2023.0.3 ALAS2023-2026-1570 Apr 13, 2026
dovecot-devel · ol 10 1:2.3.21-16.el10_1.1 ELSA-2026-13498 May 5, 2026
dovecot-devel · ol 8 1:2.3.16-7.el8_10 ELSA-2026-13830 May 6, 2026
dovecot-devel · ol 9 1:2.3.16-15.el9_7.1 ELSA-2026-13857 May 6, 2026
dovecot-flatcurve · Ubuntu 25.10 (questing) 1:2.4.1+dfsg1-5ubuntu4.1 dovecot-flatcurve 1:2.4.1+dfsg1-5ubuntu4.1 Apr 15, 2026
dovecot-gssapi · Ubuntu 22.04.1 LTS (jammy) 1:2.3.16+dfsg1-3ubuntu2.7 dovecot-gssapi 1:2.3.16+dfsg1-3ubuntu2.7 Apr 15, 2026
dovecot-gssapi · Ubuntu 24.04.5 LTS (noble) 1:2.3.21+dfsg1-2ubuntu6.3 dovecot-gssapi 1:2.3.21+dfsg1-2ubuntu6.3 Apr 15, 2026
dovecot-gssapi · Ubuntu 25.10 (questing) 1:2.4.1+dfsg1-5ubuntu4.1 dovecot-gssapi 1:2.4.1+dfsg1-5ubuntu4.1 Apr 15, 2026
dovecot-imapd · Ubuntu 22.04.1 LTS (jammy) 1:2.3.16+dfsg1-3ubuntu2.7 dovecot-imapd 1:2.3.16+dfsg1-3ubuntu2.7 Apr 15, 2026
dovecot-imapd · Ubuntu 24.04.5 LTS (noble) 1:2.3.21+dfsg1-2ubuntu6.3 dovecot-imapd 1:2.3.21+dfsg1-2ubuntu6.3 Apr 15, 2026
dovecot-imapd · Ubuntu 25.10 (questing) 1:2.4.1+dfsg1-5ubuntu4.1 dovecot-imapd 1:2.4.1+dfsg1-5ubuntu4.1 Apr 15, 2026
dovecot-ldap · Ubuntu 22.04.1 LTS (jammy) 1:2.3.16+dfsg1-3ubuntu2.7 dovecot-ldap 1:2.3.16+dfsg1-3ubuntu2.7 Apr 15, 2026
dovecot-ldap · Ubuntu 24.04.5 LTS (noble) 1:2.3.21+dfsg1-2ubuntu6.3 dovecot-ldap 1:2.3.21+dfsg1-2ubuntu6.3 Apr 15, 2026
dovecot-ldap · Ubuntu 25.10 (questing) 1:2.4.1+dfsg1-5ubuntu4.1 dovecot-ldap 1:2.4.1+dfsg1-5ubuntu4.1 Apr 15, 2026
dovecot-lmtpd · Ubuntu 22.04.1 LTS (jammy) 1:2.3.16+dfsg1-3ubuntu2.7 dovecot-lmtpd 1:2.3.16+dfsg1-3ubuntu2.7 Apr 15, 2026
dovecot-lmtpd · Ubuntu 24.04.5 LTS (noble) 1:2.3.21+dfsg1-2ubuntu6.3 dovecot-lmtpd 1:2.3.21+dfsg1-2ubuntu6.3 Apr 15, 2026
dovecot-lmtpd · Ubuntu 25.10 (questing) 1:2.4.1+dfsg1-5ubuntu4.1 dovecot-lmtpd 1:2.4.1+dfsg1-5ubuntu4.1 Apr 15, 2026
dovecot-lucene · Ubuntu 22.04.1 LTS (jammy) 1:2.3.16+dfsg1-3ubuntu2.7 dovecot-lucene 1:2.3.16+dfsg1-3ubuntu2.7 Apr 15, 2026
dovecot-managesieved · Ubuntu 22.04.1 LTS (jammy) 1:2.3.16+dfsg1-3ubuntu2.7 dovecot-managesieved 1:2.3.16+dfsg1-3ubuntu2.7 Apr 15, 2026
dovecot-managesieved · Ubuntu 24.04.5 LTS (noble) 1:2.3.21+dfsg1-2ubuntu6.3 dovecot-managesieved 1:2.3.21+dfsg1-2ubuntu6.3 Apr 15, 2026
dovecot-managesieved · Ubuntu 25.10 (questing) 1:2.4.1+dfsg1-5ubuntu4.1 dovecot-managesieved 1:2.4.1+dfsg1-5ubuntu4.1 Apr 15, 2026
dovecot-mysql · RHEL 8 1:2.3.16-7.el8_10 RHSA-2026:13830 May 15, 2026
dovecot-mysql · RHEL 9 1:2.3.16-18.el9_8 RHSA-2026:19364 May 15, 2026
dovecot-mysql · Ubuntu 22.04.1 LTS (jammy) 1:2.3.16+dfsg1-3ubuntu2.7 dovecot-mysql 1:2.3.16+dfsg1-3ubuntu2.7 Apr 15, 2026
dovecot-mysql · Ubuntu 24.04.5 LTS (noble) 1:2.3.21+dfsg1-2ubuntu6.3 dovecot-mysql 1:2.3.21+dfsg1-2ubuntu6.3 Apr 15, 2026
dovecot-mysql · Ubuntu 25.10 (questing) 1:2.4.1+dfsg1-5ubuntu4.1 dovecot-mysql 1:2.4.1+dfsg1-5ubuntu4.1 Apr 15, 2026
dovecot-mysql · almalinux 10 1:2.3.21-19.el10_2 ALSA-2026:19149 May 19, 2026
dovecot-mysql · almalinux 8 1:2.3.16-7.el8_10 ALSA-2026:13830 May 5, 2026
dovecot-mysql · almalinux 9 1:2.3.16-18.el9_8 ALSA-2026:19364 May 19, 2026
dovecot-mysql · amzn 2023 1:2.3.20-1.amzn2023.0.3 ALAS2023-2026-1570 Apr 13, 2026
dovecot-mysql · ol 10 1:2.3.21-16.el10_1.1 ELSA-2026-13498 May 5, 2026
dovecot-mysql · ol 8 1:2.3.16-7.el8_10 ELSA-2026-13830 May 6, 2026
dovecot-mysql · ol 9 1:2.3.16-15.el9_7.1 ELSA-2026-13857 May 6, 2026
dovecot-mysql-debuginfo · amzn 2023 1:2.3.20-1.amzn2023.0.3 ALAS2023-2026-1570 Apr 13, 2026
dovecot-pgsql · RHEL 8 1:2.3.16-7.el8_10 RHSA-2026:13830 May 15, 2026
dovecot-pgsql · RHEL 9 1:2.3.16-18.el9_8 RHSA-2026:19364 May 15, 2026
dovecot-pgsql · Ubuntu 22.04.1 LTS (jammy) 1:2.3.16+dfsg1-3ubuntu2.7 dovecot-pgsql 1:2.3.16+dfsg1-3ubuntu2.7 Apr 15, 2026
dovecot-pgsql · Ubuntu 24.04.5 LTS (noble) 1:2.3.21+dfsg1-2ubuntu6.3 dovecot-pgsql 1:2.3.21+dfsg1-2ubuntu6.3 Apr 15, 2026
dovecot-pgsql · Ubuntu 25.10 (questing) 1:2.4.1+dfsg1-5ubuntu4.1 dovecot-pgsql 1:2.4.1+dfsg1-5ubuntu4.1 Apr 15, 2026
dovecot-pgsql · almalinux 10 1:2.3.21-19.el10_2 ALSA-2026:19149 May 19, 2026
dovecot-pgsql · almalinux 8 1:2.3.16-7.el8_10 ALSA-2026:13830 May 5, 2026
dovecot-pgsql · almalinux 9 1:2.3.16-18.el9_8 ALSA-2026:19364 May 19, 2026
dovecot-pgsql · amzn 2023 1:2.3.20-1.amzn2023.0.3 ALAS2023-2026-1570 Apr 13, 2026
dovecot-pgsql · ol 10 1:2.3.21-16.el10_1.1 ELSA-2026-13498 May 5, 2026
dovecot-pgsql · ol 8 1:2.3.16-7.el8_10 ELSA-2026-13830 May 6, 2026
dovecot-pgsql · ol 9 1:2.3.16-15.el9_7.1 ELSA-2026-13857 May 6, 2026
dovecot-pgsql-debuginfo · amzn 2023 1:2.3.20-1.amzn2023.0.3 ALAS2023-2026-1570 Apr 13, 2026
dovecot-pigeonhole · RHEL 8 1:2.3.16-7.el8_10 RHSA-2026:13830 May 15, 2026
dovecot-pigeonhole · RHEL 9 1:2.3.16-18.el9_8 RHSA-2026:19364 May 15, 2026
dovecot-pigeonhole · almalinux 10 1:2.3.21-19.el10_2 ALSA-2026:19149 May 19, 2026
dovecot-pigeonhole · almalinux 8 1:2.3.16-7.el8_10 ALSA-2026:13830 May 5, 2026
dovecot-pigeonhole · almalinux 9 1:2.3.16-18.el9_8 ALSA-2026:19364 May 19, 2026
dovecot-pigeonhole · amzn 2023 1:2.3.20-1.amzn2023.0.3 ALAS2023-2026-1570 Apr 13, 2026
dovecot-pigeonhole · ol 10 1:2.3.21-16.el10_1.1 ELSA-2026-13498 May 5, 2026
dovecot-pigeonhole · ol 8 1:2.3.16-7.el8_10 ELSA-2026-13830 May 6, 2026
dovecot-pigeonhole · ol 9 1:2.3.16-15.el9_7.1 ELSA-2026-13857 May 6, 2026
dovecot-pigeonhole-debuginfo · amzn 2023 1:2.3.20-1.amzn2023.0.3 ALAS2023-2026-1570 Apr 13, 2026
dovecot-pop3d · Ubuntu 22.04.1 LTS (jammy) 1:2.3.16+dfsg1-3ubuntu2.7 dovecot-pop3d 1:2.3.16+dfsg1-3ubuntu2.7 Apr 15, 2026
dovecot-pop3d · Ubuntu 24.04.5 LTS (noble) 1:2.3.21+dfsg1-2ubuntu6.3 dovecot-pop3d 1:2.3.21+dfsg1-2ubuntu6.3 Apr 15, 2026
dovecot-pop3d · Ubuntu 25.10 (questing) 1:2.4.1+dfsg1-5ubuntu4.1 dovecot-pop3d 1:2.4.1+dfsg1-5ubuntu4.1 Apr 15, 2026
dovecot-sieve · Ubuntu 22.04.1 LTS (jammy) 1:2.3.16+dfsg1-3ubuntu2.7 dovecot-sieve 1:2.3.16+dfsg1-3ubuntu2.7 Apr 15, 2026
dovecot-sieve · Ubuntu 24.04.5 LTS (noble) 1:2.3.21+dfsg1-2ubuntu6.3 dovecot-sieve 1:2.3.21+dfsg1-2ubuntu6.3 Apr 15, 2026
dovecot-sieve · Ubuntu 25.10 (questing) 1:2.4.1+dfsg1-5ubuntu4.1 dovecot-sieve 1:2.4.1+dfsg1-5ubuntu4.1 Apr 15, 2026
dovecot-solr · Ubuntu 22.04.1 LTS (jammy) 1:2.3.16+dfsg1-3ubuntu2.7 dovecot-solr 1:2.3.16+dfsg1-3ubuntu2.7 Apr 15, 2026
dovecot-solr · Ubuntu 24.04.5 LTS (noble) 1:2.3.21+dfsg1-2ubuntu6.3 dovecot-solr 1:2.3.21+dfsg1-2ubuntu6.3 Apr 15, 2026
dovecot-solr · Ubuntu 25.10 (questing) 1:2.4.1+dfsg1-5ubuntu4.1 dovecot-solr 1:2.4.1+dfsg1-5ubuntu4.1 Apr 15, 2026
dovecot-sqlite · Ubuntu 22.04.1 LTS (jammy) 1:2.3.16+dfsg1-3ubuntu2.7 dovecot-sqlite 1:2.3.16+dfsg1-3ubuntu2.7 Apr 15, 2026
dovecot-sqlite · Ubuntu 24.04.5 LTS (noble) 1:2.3.21+dfsg1-2ubuntu6.3 dovecot-sqlite 1:2.3.21+dfsg1-2ubuntu6.3 Apr 15, 2026
dovecot-sqlite · Ubuntu 25.10 (questing) 1:2.4.1+dfsg1-5ubuntu4.1 dovecot-sqlite 1:2.4.1+dfsg1-5ubuntu4.1 Apr 15, 2026
dovecot-submissiond · Ubuntu 22.04.1 LTS (jammy) 1:2.3.16+dfsg1-3ubuntu2.7 dovecot-submissiond 1:2.3.16+dfsg1-3ubuntu2.7 Apr 15, 2026
dovecot-submissiond · Ubuntu 24.04.5 LTS (noble) 1:2.3.21+dfsg1-2ubuntu6.3 dovecot-submissiond 1:2.3.21+dfsg1-2ubuntu6.3 Apr 15, 2026
dovecot-submissiond · Ubuntu 25.10 (questing) 1:2.4.1+dfsg1-5ubuntu4.1 dovecot-submissiond 1:2.4.1+dfsg1-5ubuntu4.1 Apr 15, 2026
dovecot23 · sles 15.6 2.3.21.1-150200.76.1 SUSE-SU-2026:4139-1 Sep 14, 2026
dovecot23 · sles 15.7 2.3.21.1-150200.76.1 SUSE-SU-2026:4139-1 Sep 14, 2026
dovecot24 · opensuse-leap 16.0 2.4.3-160000.1.1 OPENSUSE-SU-2026:20554-1 Apr 16, 2026
dovecot24 · sles 16.0 2.4.3-160000.1.1 SUSE-SU-2026:21208-1 Apr 16, 2026

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