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CVE-2024-23184: Having a large number of address headers (From, To, Cc, Bcc, etc.) becomes excessively CPU intensive
by Aki Tuomi 14 Aug '24

14 Aug '24

Affected product: Dovecot IMAP Server Internal reference: DOV-6464 Vulnerability type: CWE-770 (Allocation of Resources Without Limits or Throttling) Vulnerable version: 2.2, 2.3 Vulnerable component: lib-mail Report confidence: Confirmed Solution status: Fixed in 2.3.21.1 Researcher credits: Vendor internal discovery Vendor notification: 2024-01-30 CVE reference: CVE-2024-23184 CVSS: 5.0 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N) Vulnerability Details: 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. The main problem is that each header line's address is added to the end of a linked list. This is done by walking the whole linked list, which becomes more inefficient the more addresses there are. Workaround: One can implement restrictions on address headers on MTA component preceding Dovecot. Fix: Install non-vulnerable version of Dovecot. Patch can be found at https://github.com/dovecot/core/compare/8e4c42d%5E...1481c04.patch

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CVE-2024-23185: Very large headers can cause resource exhaustion when parsing message
by Aki Tuomi 14 Aug '24

14 Aug '24

Affected product: Dovecot IMAP Server Internal reference: DOV-6601 Vulnerability type: CWE-770 (Allocation of Resources Without Limits or Throttling) Vulnerable version: 2.2, 2.3 Vulnerable component: lib-mail Report confidence: Confirmed Solution status: Fixed in 2.3.21.1 Researcher credits: Vendor internal discovery Vendor notification: 2024-01-31 CVE reference: CVE-2024-23185 CVSS: 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) Vulnerability Details: Very large headers can cause resource exhaustion when parsing message. The message-parser normally reads reasonably sized chunks of the message. However, when it feeds them to message-header-parser, it starts building up "full_value" buffer out of the smaller chunks. The full_value buffer has no size limit, so large headers can cause large memory usage. It doesn't matter whether it's a single long header line, or a single header split into multiple lines. This bug exists in all Dovecot versions. Incoming mails typically have some size limits set by MTA, so even largest possible header size may still fit into Dovecot's vsz_limit. So attackers probably can't DoS a victim user this way. A user could APPEND larger mails though, allowing them to DoS themselves (although maybe cause some memory issues for the backend in general). Workaround: One can implement restrictions on headers on MTA component preceding Dovecot. Fix: Install non-vulnerable version of Dovecot. Patch can be found at https://github.com/dovecot/core/compare/f020e13%5E...ce88c33.patch

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Pigeonhole v0.5.21.1 released
by Aki Tuomi 14 Aug '24

14 Aug '24

Hi all, we are releasing new version of Pigeonhole. https://pigeonhole.dovecot.org/releases/2.3/dovecot-2.3-pigeonhole-0.5.21.1… https://pigeonhole.dovecot.org/releases/2.3/dovecot-2.3-pigeonhole-0.5.21.1… Binary packages in https://repo.dovecot.org/ Docker images in https://hub.docker.com/r/dovecot/dovecot Kind regards, Aki Tuomi Open-Xchange oy --- - sieve: When saving to local storage failed after a successful action in sieve (e.g. redirect, vacation), the mail was reported as successfully delivered, although it was lost locally.

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Dovecot v2.3.21.1 released
by Aki Tuomi 14 Aug '24

14 Aug '24

Hi all, we are releasing a CVE patch release 2.3.21.1. https://dovecot.org/releases/2.3/dovecot-2.3.21.1.tar.gz https://dovecot.org/releases/2.3/dovecot-2.3.21.1.tar.gz.sig Binary packages in https://repo.dovecot.org/ Docker images in https://hub.docker.com/r/dovecot/dovecot Kind regards, Aki Tuomi Open-Xchange oy --- - 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. - oauth2: Dovecot would send client_id and client_secret as POST parameters to introspection server. These need to be optionally in Basic auth instead as required by OIDC specification. - oauth2: JWT key type check was too strict. - oauth2: JWT token audience was not validated against client_id as required by OIDC specification. - oauth2: XOAUTH2 and OAUTHBEARER mechanisms were not giving out protocol specific error message on all errors. This broke OIDC discovery. - oauth2: JWT aud validation was not performed if aud was missing from token, but was configured on Dovecot.

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Pigeonhole v0.5.21 released
by Aki Tuomi 15 Sep '23

15 Sep '23

Hi all! We are pleased to release v0.5.21 of Pigeonhole. https://pigeonhole.dovecot.org/releases/2.3/dovecot-2.3-pigeonhole-0.5.21.t… https://pigeonhole.dovecot.org/releases/2.3/dovecot-2.3-pigeonhole-0.5.21.t… Binary packages in https://repo.dovecot.org/ Docker images in https://hub.docker.com/r/dovecot/dovecot Regards, Aki Tuomi Open-Xchange oy --- - sieve: Using the deleteheader action on a message with a broken/invalid header can cause the Sieve interpreter to crash with an assert panic. This can happen e.g. when the message is missing the empty EOH line between the headers and the body of the message. Fixes: Panic: file edit-mail.c: line 820 (edit_mail_headers_parse): assertion failed: (body_offset > 0). - sieve: Pigeonhole added an extra Message-ID header during mail forwarding when the existing one was invalid. Now it adds the Message-ID only if it is entirely missing. Existing Message-ID(s) are left unchanged.

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Dovecot v2.3.21 released
by Aki Tuomi 15 Sep '23

15 Sep '23

Hi all! We are pleased to release v2.3.21 of Dovecot. https://dovecot.org/releases/2.3/dovecot-2.3.21.tar.gz https://dovecot.org/releases/2.3/dovecot-2.3.21.tar.gz.sig Binary packages in https://repo.dovecot.org/ Docker images in https://hub.docker.com/r/dovecot/dovecot Regards, Aki Tuomi Open-Xchange oy --- * lib-oauth2: Allow JWT tokens to be validated with missing typ field. The typ field is left out by some key issuers to conserve space, notably kubernetes. Now missing typ is tolerated, but if present, it still must be "jwt". + auth: Auth passdb and userdb reply can contain "event_<name>=value" which will be added to login event and mail user event respectively. + lib-master: Set process title during various initialization stages to clearly describe what the process is waiting on. + lib-storage: The mail_temp_scan_interval is now fuzzed incrementing it by 0..30% based on username's hash to reduce the chance of load spikes . + lib-storage: The temp file scan has been moved from the open of the mailbox to the close, to reduce the latency perceived by users. + stats: If metric has fields specified, all these fields are exported as counters to prometheus exposition. See https://doc.dovecot.org/configuration_manual/stats/openmetrics/. - *-login: Processes might have crashed when a SSL connection disconnect s uncleanly. - acl: When plugin was loaded \HasChildren and \HasNoChildren flags were calculated incorrectly for mailboxes containing '*' and '%' in their names. - auth: Crash occured if a connection to PostgreSQL database server failed during startup. - auth: Logins with invalid passwords (e.g. unknown scheme) in passdb were failing with "password mismatch" instead of "internal error". - auth: XOAUTH2 and OAUTHBEARER mechanisms were not giving out protocol specific error message on all errors. This especially broke OIDC discovery. - dbox: When last_temp_file_scan header wasn't set (especially after dsync migration), the next mailbox open always triggers the temp file scan. This could have caused a load spike after migrations. Fixed by using the mailbox directory's atime when the header isn't set, which usually moves the scan time into the future. - dict-redis: A crash would occur on transaction rollback. - dsync: Infinite loop causing out of memory would occur when handling mailbox deletion from remote end and hierarchy separators would differ. - dsync: Incremental dsync failed for folder names ending with '%', unless BROKENCHAR was set. Also folder names with '%' elsewhere in them caused each incremental dsync to unnecessarily rename the folder to a temporary name and back. v2.3.19 regression. - imap-hibernate: If an IMAP client unhibernation timed out with "(version received)", the unhibernation could still have successfully finished later on and continued working normally. This was rather confusing, because imap-hibernate already logged that the client got disconnected. Avoid this by forcing the connection to shutdown on unhibernation timeout. - imapc: Crashed when a folder mapped through the virtual plugin disappears from the storage. - imapc: EXPUNGE, EXISTS or FETCH replies from a server for a previously selected mailbox could have been processed as if they belonged to the new mailbox currently being selected. This could have caused warnings. - lib-http: Dovecot HTTP server (doveadm, stats/openmetrics) may have disconnected HTTP clients before the response is fully sent. This happened only on busy servers where kernel's socket buffers were rather full. - lib-http: Fixed a potential crash on http-server if a client disconnected early. v2.3.18 regression. - lib-index: Index file corruption could have caused a crash. Fixes: Panic: file mail-transaction-log-view.c: line 165 (mail_transaction_log_view_set): assertion failed: (min_file_seq <= max_file_seq). - lib-index: Purging an existing >1GB cache file can crash. Now cache files still above 1GB after purging are removed. Fixes: Panic: file mail-index-util.c: line 10 (mail_index_uint32_to_offset): assertion failed: (offset < 0x40000000) - lib-lua: A HTTP client could not resolve DNS names in mail processes, because it expected "the dns-client" socket to exist in the current directory. - lib-oauth2: Dovecot would send client_id and client_secret as POST parameters to the introspection server. These need to be optionally in Basic auth instead. - lib-oauth2: JWT aud validation was not performed if aud was missing from a token, but was configured on Dovecot. - lib-oauth2: JWT key type check was too strict. - lib-oauth2: JWT token audience was not validated against client_id as required by the specification. - lib-ssl-iostream: Using the ssl_require_crl=yes setting may have caused CRL check failures for outgoing SSL/TLS connections, although it was supposed to affect checking CRLs only for client-side SSL certificates. v2.3.17 regression. - lib-sql: MySQL driver leaked memory when connection failed. - lib-storage: Various fixes when running into out of disk space. - master: Service idle_kill setting didn't work properly on busy servers. It was very unlikely that any process was idling long enough to become killed. Also the idle_kill handling code was using quite a lot of CPU on the master process when there were a lot of processes (e.g. imap). The new behavior is to track the lowest number of idling processes every idle_kill time interval and then kill that many idling processes. - mdbox: Temp file scan was done for always empty directories. - mdbox: The fdatasync() call was done in wrong parent directory when writing mails. Also on a failure it crashed instead of logging an error. - notify_status: The plugin crashes if any user initialization fails. - pop3: Sending command with the ':' character caused an assert-crash. v2.3.18 regression. Fixes: Panic: event_reason_code_prefix(): name has ':' - stats: Fix panic when a nonexistent event exporter was referenced while adding a new metric dynamically via doveadm stats add. This produces a proper error now. - stats: If process exported a lot of events and then exited, some of the last events may have become lost. - stats: Invalid Prometheus label names were created with specific histogram group_by configurations. Prometheus rejected these labels. - welcome: The plugin didn't execute in some situations that created INBOX but didn't open it, e.g. if GETMETADATA was used before the INBOX was opened.

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Pigeonhole v0.5.20 released
by Aki Tuomi 22 Dec '22

22 Dec '22

We are pleased to release v0.5.20 of Pigeonhole. https://pigeonhole.dovecot.org/releases/2.3/dovecot-2.3-pigeonhole-0.5.20.t… https://pigeonhole.dovecot.org/releases/2.3/dovecot-2.3-pigeonhole-0.5.20.t… Binary packages in https://repo.dovecot.org/ Docker images in https://hub.docker.com/r/dovecot/dovecot Regards, Aki Tuomi Open-Xchange oy -- * No changes - release done to keep version numbers synced.

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Dovecot v2.3.20 released
by Aki Tuomi 22 Dec '22

22 Dec '22

We are pleased to release v2.3.20 of Dovecot. https://dovecot.org/releases/2.3/dovecot-2.3.20.tar.gz https://dovecot.org/releases/2.3/dovecot-2.3.20.tar.gz.sig Binary packages in https://repo.dovecot.org/ Docker images in https://hub.docker.com/r/dovecot/dovecot Regards, Aki Tuomi Open-Xchange oy -- + Add dsync_features=no-header-hashes. When this setting is enabled and one dsync side doesn't support mail GUIDs (i.e. imapc), there is no fallback to using header hashes. Instead, dsync assumes that all mails with identical IMAP UIDs contains the same mail contents. This can significantly improve dsync performance with some IMAP servers that don't support caching Date/Message-ID headers. + lua: HTTP client has more settings now, see https://doc.dovecot.org/admin_manual/lua/#dovecot.http.client + replicator: "doveadm replicator status" command now outputs when the next sync is expected for the user. - LAYOUT=index: duplicate GUIDs were not cleaned out. Also the list recovery was not optimal. - auth: Assert crash would occur when iterating multiple userdb backends. - director: Logging into director using master user with auth_master_user_separator character redirected user to a wrong backend, unless master_user_separator setting was also set to the same value. Merged these into auth_master_user_separator. - dsync: Couldn't always fix folder GUID conflicts automatically with Maildir format. This resulted in replication repeatedly failing with "Remote lost mailbox GUID". - dsync: Failed to migrate INBOX when using namespace prefix=INBOX/, resulting in "Remote lost mailbox GUID" errors. - dsync: INBOX was created too early with namespace prefix=INBOX/, resulting a GUID conflict. This may have been resolved automatically, but not always. - dsync: v2.3.18 regression: Wrong imapc password with dsync caused Panic: file lib-event.c: line 506 (event_pop_global): assertion failed: (event == current_global_event) - imapc: Requesting STATUS for a mailbox with imapc and INDEXPVT configured did not return correct (private) unseen counts. - lib-dict: Process would crash when committing data to redis without dict proxy. - lib-mail: Corrupted cached BODYSTRUCTURE caused panic during FETCH. Fixes: Panic: file message-part-data.c: line 579 (message_part_is_attachment): assertion failed: (data != NULL). v2.3.13 regression. - lib-storage: mail_attribute_dict with dict-sql failed when it tried to lookup empty dict keys. - lib: ioloop-kqueue was missing include breaking some BSD builds. - lua-http: Dovecot Lua HTTP client could not resolve DNS names in mail processes, because it expected "dns-client" socket to exist in the current directory. - oauth2: Using %{oauth2:name} variables could cause useless introspections. - pop3: Sending POP3 command with ':' character caused an assert-crash. v2.3.18 regression. - replicator: Replication queue had various issues, potentially causing replication requests to become stuck. - stats: Invalid Prometheus label names were created with specific

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CVE-2022-30550: Privilege escalation possible in dovecot when similar master and non-master passdbs are used
by Aki Tuomi 07 Jul '22

07 Jul '22

Affected product: Dovecot IMAP Server Internal reference: DOV-5320 Vulnerability type: Improper Access Control (CWE-284) Vulnerable version: 2.2 Vulnerable component: submission Report confidence: Confirmed Solution status: Fixed in main Researcher credits: Julian Brook (julezman) Vendor notification: 2022-05-06 CVE reference: CVE-2022-30550 CVSS: 6.8 (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N) Vulnerability Details: When two passdb configuration entries exist in Dovecot configuration, which have the same driver and args settings, the incorrect username_filter and mechanism settings can be applied to passdb definitions. These incorrectly applied settings can lead to an unintended security configuration and can permit privilege escalation with certain configurations involving master user authentication. Dovecot documentation does not advise against the use of passdb definitions which have the same driver and args settings. One such configuration would be where an administrator wishes to use the same pam configuration or passwd file for both normal and master users but use the username_filter setting to restrict which of the users is able to be a master user. Risk: If same passwd file or PAM is used for both normal and master users, it is possible for attacker to become master user. Workaround: Always authenticate master users from different source than regular users, e.g. using a separate passwd file. Alternatively, you can use global ACLs to ensure that only legimate master users have priviledged access. Fix: This has been fixed in main branch. See https://github.com/dovecot/core/compare/7bad6a24%5E..a1022072.patch

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v2.3.19.1 released
by Aki Tuomi 14 Jun '22

14 Jun '22

Hi everyone! Due to a severe bug in doveadm deduplicate, we are releasing patch release 2.3.19.1. Please find it at locations below: https://dovecot.org/releases/2.3/dovecot-2.3.19.1.tar.gz https://dovecot.org/releases/2.3/dovecot-2.3.19.1.tar.gz.sig Binary packages in https://repo.dovecot.org/ Docker images in https://hub.docker.com/r/dovecot/dovecot Aki Tuomi Open-Xchange oy --- - doveadm deduplicate: Non-duplicate mails were deleted. v2.3.19 regression. - auth: Crash would occur when iterating multiple backends. Fixes: Panic: file userdb-blocking.c: line 125 (userdb_blocking_iter_next): assertion failed: (ctx->conn != NULL)

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