Dovecot-news January 2021

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Ubuntu packages
by Aki Tuomi 06 Jan '21

06 Jan '21

Hi! Since Ubuntu 20.04 LTS is nowadays available, we have dropped 16.04 support from 2.3.13 as per policy of supporting two latest releases of operating system. Dovecot 2.3.11.3 is latest version we provide packages for 16.04. Please find Ubuntu 20.04 packages at https://repo.dovecot.org/ Kind regards, Aki Tuomi Open-Xchange oy

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CVE-2020-25275: MIME parsing crashes with particular messages
by Aki Tuomi 04 Jan '21

04 Jan '21

Open-Xchange Security Advisory 2021-01-04 Product: Dovecot Vendor: OX Software GmbH Internal reference: DOV-4113 (Bug ID) Vulnerability type: CWE-20: Improper Input Validation Vulnerable version: 2.3.11-2.3.11.3 Vulnerable component: lda, lmtp, imap Report confidence: Confirmed Solution status: Fixed by Vendor Fixed version: 2.3.13 Vendor notification: 2020-09-10 Solution date: 2020-09-14 Public disclosure: 2021-01-04 CVE reference: CVE-2020-25275 CVSS: 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L) Researcher credit: Innokentii Sennovskiy (Rumata888) from BI.ZONE Vulnerability Details: Mail delivery / parsing crashed when the 10 000th MIME part was message/rfc822 (or if parent was multipart/digest). This happened due to earlier MIME parsing changes for CVE-2020-12100. Risk: Malicious sender can crash dovecot repeatedly by sending / uploading message with more than 10 000 MIME parts. Workaround: These are usually dropped by MTA, where the mitigation can also be applied. Solution: Operators should update to 2.3.13 or later version.

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CVE-2020-24386: IMAP hibernation allows accessing other peoples mail
by Aki Tuomi 04 Jan '21

04 Jan '21

Open-Xchange Security Advisory 2021-01-04 Product: Dovecot Vendor: OX Software GmbH Internal reference: DOP-2009 (Bug ID) Vulnerability type: CWE-150: Improper Neutralization of Escape, Meta, or Control Sequences Vulnerable version: 2.2.26-2.3.11.3 Vulnerable component: imap Report confidence: Confirmed Solution status: Fixed by Vendor Fixed version: 2.3.13 Vendor notification: 2020-08-17 Solution date: 2020-08-27 Public disclosure: 2021-01-04 CVE reference: CVE-2020-24386 CVSS: 8.2 (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N) Vulnerability Details: When imap hibernation is active, an attacker can cause Dovecot to discover file system directory structure and access other users' emails using specially crafted command. The attacker must have valid credentials to access the mail server. Risk: Attacker can access other users' emails and filesystem information. Workaround: Operators can choose to disable IMAP hibernation. IMAP hibernation is not on by default. To ensure imap hibernation is disabled, make sure imap_hibernate_timeout is set to 0 or unset. Solution: Operators should update to 2.3.13 or later version.

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Pigeonhole v0.5.13 released
by Aki Tuomi 04 Jan '21

04 Jan '21

We are pleased to release pigeonhole 0.5.13. You can download it from locations below: https://pigeonhole.dovecot.org/releases/2.3/dovecot-2.3-pigeonhole-0.5.13.t… https://pigeonhole.dovecot.org/releases/2.3/dovecot-2.3-pigeonhole-0.5.13.t… Binary packages in https://repo.dovecot.org/ Docker images in https://hub.docker.com/r/dovecot/dovecot Aki Tuomi Open-Xchange oy --- - duplicate: The test was handled badly in a multiscript (sieve_before, sieve_after) scenario in which an earlier script in the sequence with a duplicate test succeeded, while a later script caused a runtime failure. In that case, the message is recorded for duplicate tracking, while the message may not actually have been delivered in the end. - editheader: Sieve interpreter entered infinite loop at startup when the "editheader" configuration listed an invalid header name. This problem can only be triggered by the administrator. - relational: The Sieve relational extension can cause a segfault at compile time. This is triggered by invalid script syntax. The segfault happens when this match type is the last argument of the test command. This situation is not possible in a valid script; positional arguments are normally present after that, which would prevent the segfault. - sieve: For some Sieve commands the provided mailbox name is not properly checked for UTF-8 validity, which can cause assert crashes at runtime when an invalid mailbox name is encountered. This can be caused by the user by writing a bad Sieve script involving the affected commands ("mailboxexists", "specialuse_exists"). This can be triggered by the remote sender only when the user has written a Sieve script that passes message content to one of the affected commands. - sieve: Large sequences of 8-bit octets passed to certain Sieve commands that create or modify message headers that allow UTF-8 text (vacation, notify and addheader) can cause the delivery or IMAP process (when IMAPSieve is used) to enter a memory-consuming semi-infinite loop that ends when the process exceeds its memory limits. Logged in users can cause these hangs only for their own processes.

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Dovecot v2.3.13 released
by Aki Tuomi 04 Jan '21

04 Jan '21

We are pleased to release v2.3.13. Please find it from locations below: https://dovecot.org/releases/2.3/dovecot-2.3.13.tar.gz https://dovecot.org/releases/2.3/dovecot-2.3.13.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 --- * CVE-2020-24386: Specially crafted command can cause IMAP hibernate to allow logged in user to access other people's emails and filesystem information. * Metric filter and global event filter variable syntax changed to a SQL-like format. See https://doc.dovecot.org/configuration_manual/event_filter/ * auth: Added new aliases for %{variables}. Usage of the old ones is possible, but discouraged. * auth: Removed RPA auth mechanism, SKEY auth mechanism, NTLM auth mechanism and related password schemes. * auth: Removed passdb-sia, passdb-vpopmail and userdb-vpopmail. * auth: Removed postfix postmap socket + auth: Added new fields for auth server events. These fields are now also available for all auth events. See https://doc.dovecot.org/admin_manual/list_of_events/#authentication-server for details. + imap-hibernate: Added imap_client_hibernated, imap_client_unhibernated and imap_client_unhibernate_retried events. See https://doc.dovecot.org/admin_manual/list_of_events/ for details. + lib-index: Added new mail_index_recreated event. See https://doc.dovecot.org/admin_manual/list_of_events/#mail-index-recreated + lib-sql: Support TLS options for cassandra driver. This requires cpp-driver v2.15 (or later) to work reliably. + lib-storage: Missing $HasAttachment / $HasNoAttachment flags are now added to existing mails if mail_attachment_detection_option=add-flags and it can be done inexpensively. + login proxy: Added login_proxy_max_reconnects setting (default 3) to control how many reconnections are attempted. + login proxy: imap/pop3/submission/managesieve proxying now supports reconnection retrying on more than just connect() failure. Any error except a non-temporary authentication failure will result in reconnect attempts. - auth: Lua passdb/userdb leaks stack elements per call, eventually causing the stack to become too deep and crashing the auth or auth-worker process. - auth: SASL authentication PLAIN mechanism could be used to trigger read buffer overflow. However, this doesn't seem to be exploitable in any way. - auth: v2.3.11 regression: GSSAPI authentication fails because dovecot disallows NUL bytes for it. - dict: Process used too much CPU when iterating keys, because each key used a separate write() syscall. - doveadm-server: Crash could occur if logging was done outside command handling. For example http-client could have done debug logging afterwards, resulting in either segfault or Panic: file http-client.c: line 642 (http_client_context_close): assertion failed: (cctx->clients_list == NULL). - doveadm-server: v2.3.11 regression: Trying to connect to doveadm server process via starttls assert-crashed if there were no ssl=yes listeners: Panic: file master-service-ssl.c: line 22 (master_service_ssl_init): assertion failed: (service->ssl_ctx_initialized). - fts-solr: HTTP requests may have assert-crashed: Panic: file http-client-request.c: line 1232 (http_client_request_send_more): assertion failed: (req->payload_input != NULL) - imap: IMAP NOTIFY could crash with a segmentation fault due to a bad configuration that causes errors. Sending the error responses to the client can cause the segmentation fault. This can for example happen when several namespaces use the same mail storage location. - imap: IMAP NOTIFY used on a shared namespace that doesn't actually exist (e.g. public namespace for a nonexistent user) can crash with a panic: Panic: Leaked view for index /tmp/home/asdf/mdbox/dovecot.list.index: Opened in (null):0 - imap: IMAP session can crash with QRESYNC extension if many changes are done before asking for expunged mails since last sync. - imap: Process might hang indefinitely if client disconnects after sending some long-running commands pipelined, for example FETCH+LOGOUT. - lib-compress: Mitigate crashes when configuring a not compiled in compression. Errors with compression configuration now distinguish between not supported and unknown. - lib-compression: Using xz/lzma compression in v2.3.11 could have written truncated output in some situations. This would result in "Broken pipe" read errors when trying to read it back. - lib-compression: zstd compression could have crashed in some situations: Panic: file ostream.c: line 287 (o_stream_sendv_int): assertion failed: (!stream->blocking) - lib-dict: dict client could have crashed in some rare situations when iterating keys. - lib-http: Fix several assert-crashes in HTTP client. - lib-index: v2.3.11 regression: When mails were expunged at the same time as lots of new content was being saved to the cache (e.g. cache file was lost and is being re-filled) a deadlock could occur with dovecot.index.cache / dovecot.index.log. - lib-index: v2.3.11 regression: dovecot.index.cache file was being purged (rewritten) too often when it had a field that hadn't been accessed for over 1 month, but less than 2 months. Every cache file change caused a purging in this situation. - lib-mail: MIME parts were not returned correctly by Dovecot MIME parser. Regression caused by fixing CVE-2020-12100. - lib-mail: When max nested MIME parts were reached, IMAP BODYSTRUCTURE was written in a way that may have caused confusion for both IMAP clients and Dovecot itself when parsing it. The truncated part is now written out using application/octet-stream MIME type. - lib-mail: v2.3.11 regression: Mail delivery / parsing crashed when the 10000th MIME part was message/rfc822 (or if parent was multipart/digest): Panic: file message-parser.c: line 167 (message_part_append): assertion failed: (ctx->total_parts_count <= ctx->max_total_mime_parts). - lib-oauth2: Dovecot incorrectly required oauth2 server introspection reply to contain username with invalid token. - lib-ssl-iostream, lib-dcrypt: Fix building with OpenSSL that has deprecated APIs disabled. - lib-storage: When mail's size is different from the cached one (in dovecot.index.cache or Maildir S=size in the filename), this is handled by logging "Cached message size smaller/larger than expected" error. However, in some situations this also ended up crashing with: Panic: file istream.c: line 315 (i_stream_read_memarea): assertion failed: (old_size <= _stream->pos - _stream->skip). - lib-storage: v2.3 regression: Copying/moving mails was taking much more memory than before. This was mainly visible when copying/moving thousands of mails in a single transaction. - lib-storage: v2.3.11 regression: Searching messages assert-crashed (without FTS): Panic: file message-parser.c: line 174 (message_part_finish): assertion failed: (ctx->nested_parts_count > 0). - lib: Dovecot v2.3 moved signal handlers around in ioloops, causing more CPU usage than in v2.2. - lib: Fixed JSON parsing: '\' escape sequence may have wrongly resulted in error if it happened to be at read boundary. Any NUL characters and '\u0000' will now result in parsing error instead of silently truncating the data. - lmtp, submission: Server may hang if SSL client connection disconnects during the delivery. If this happened repeated, it could have ended up reaching process_limit and preventing any further lmtp/submission deliveries. - lmtp: Proxy does not always properly log TLS connection problems as errors; in some cases, only a debug message is logged if enabled. - lmtp: The LMTP service can hang when commands are pipelined. This can particularly occur when one command in the middle of the pipeline fails. One example of this occurs for proxied LMTP transactions in which the final DATA or BDAT command is pipelined after a failing RCPT command. - login-proxy: The login_source_ips setting has no effect, and therefore the proxy source IPs are not cycled through as they should be. - master: Process was using 100% CPU in some situations when a broken service was being throttled. - pop3-login: POP3 login would fail with "Input buffer full" if the initial response for SASL was too long. - stats: Crash would occur when generating openmetrics data for metrics using aggregating functions.

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Dovecot-news January 2021