Multiple buffer overflows in Cyrus Sieve / libSieve 2.1.2 and earlier allow remote attackers to execute arbitrary code via (1) a long header name, (2) a long IMAP flag, or (3) a script that generates a large number of errors that overflow the resulting error string.

Multiple buffer overflows in Cyrus SASL library 2.1.9 and earlier allow remote attackers to cause a denial of service and possibly execute arbitrary code via (1) long inputs during user name canonicalization, (2) characters that need to be escaped during LDAP authentication using saslauthd, or (3) an off-by-one error in the log writer, which does not allocate space for the null character that terminates a string.

Last updated 25 August 2025

Cyrus IMAP 2.5.x before 2.5.14 and 3.x before 3.0.12 allows privilege escalation because an HTTP request may be interpreted in the authentication context of an unrelated previous request that arrived over the same connection.

In the mboxlistdofind function in imap/mboxlist.c in Cyrus IMAP before 3.0.4, an off-by-one error in prefix calculation for the LIST command caused use of uninitialized memory, which might allow remote attackers to obtain sensitive information or cause a denial of service (daemon crash) via a 'LIST "" "Other Users"' command.

Buffer overflow in digestmd5.c CVS release 1.170 (also referred to as digestmda5.c), as used in the DIGEST-MD5 SASL plugin for Cyrus-SASL but not in any official releases, allows remote attackers to execute arbitrary code.

Multiple buffer overflows in Cyrus IMAPd before 2.2.11 may allow attackers to execute arbitrary code via (1) an off-by-one error in the imapd annotate extension, (2) an off-by-one error in "cached header handling," (3) a stack-based buffer overflow in fetchnews, or (4) a stack-based buffer overflow in imapd.

SQL injection vulnerability in the LDAP and MySQL authentication patch for Cyrus SASL 1.5.24 and 1.5.27 allows remote attackers to execute arbitrary SQL commands and log in as arbitrary POP mail users via the password.

imap/nntpd.c in the NNTP server (nntpd) for Cyrus IMAPd 2.4.x before 2.4.12 allows remote attackers to bypass authentication by sending an AUTHINFO USER command without sending an additional AUTHINFO PASS command.

The indexurlfetch function in index.c in Cyrus IMAP 2.3.x before 2.3.19, 2.4.x before 2.4.18, 2.5.x before 2.5.4 allows remote attackers to obtain sensitive information or possibly have unspecified other impact via vectors related to the urlfetch range, which triggers an out-of-bounds heap read.

Integer overflow in the indexurlfetch function in imap/index.c in Cyrus IMAP 2.3.19, 2.4.18, and 2.5.6 allows remote attackers to have unspecified impact via vectors related to urlfetch range checks and the sectionoffset variable. NOTE: this vulnerability exists because of an incomplete fix for CVE-2015-8076.

Integer overflow in the indexurlfetch function in imap/index.c in Cyrus IMAP 2.3.19, 2.4.18, and 2.5.6 allows remote attackers to have unspecified impact via vectors related to urlfetch range checks and the startoctet variable. NOTE: this vulnerability exists because of an incomplete fix for CVE-2015-8076.

Cyrus IMAP before 3.4.2 allows remote attackers to cause a denial of service (multiple-minute daemon hang) via input that is mishandled during hash-table interaction. Because there are many insertions into a single bucket, strcmp becomes slow. This is fixed in 3.4.2, 3.2.8, and 3.0.16.

The (1) libsasl and (2) libsasl2 libraries in Cyrus-SASL 2.1.18 and earlier trust the SASLPATH environment variable to find all available SASL plug-ins, which allows local users to execute arbitrary code by modifying the SASLPATH to point to malicious programs.

An issue was discovered in cyrus-imapd in Cyrus IMAP through 3.12.2. The LOCALDELETE command bypassed ACL checks. An authenticated but non-admin user could invoke the admin-only LOCALDELETE IMAP command and delete mailboxes for which they had no permissions.

An issue was discovered in Cyrus IMAP before 2.5.15, 3.0.x before 3.0.13, and 3.1.x through 3.1.8. If sieve script uploading is allowed (3.x) or certain non-default sieve options are enabled (2.x), a user with a mail account on the service can use a sieve script containing a fileinto directive to create any mailbox with administrator privileges, because of folder mishandling in autosievecreatefolder() in imap/lmtpsieve.c.

Stack-based buffer overflow in pop3d in Cyrus IMAPD (cyrus-imapd) 2.3.2, when the popsubfolders option is enabled, allows remote attackers to execute arbitrary code via a long USER command.

An issue was discovered in cyrus-imapd in Cyrus IMAP through 3.12.2. LISTRIGHTS os not limited to users with admin access. An authenticated user could call IMAP LISTRIGHTS against any mailbox they could name and learn what principals had what access to it. (This action should have been restricted to users with admin access on the target mailbox.)

An issue was discovered in cyrus-imapd in Cyrus IMAP through 3.12.2. There is an ESEARCH cross-user content oracle. By using the ESEARCH command, an authenticated IMAP user could enumerate folder names under any account they could name. Search would return UIDs of messages matching the search, creating a content oracle (without allowing arbitrary reads of the target's content).

Cyrus IMAP before 3.2.7, and 3.3.x and 3.4.x before 3.4.1, allows remote authenticated users to bypass intended access restrictions on server annotations and consequently cause replication to stall.

An issue was discovered in cyrus-imapd in Cyrus IMAP through 3.12.2. URLAUTH token forgery can occur via a missing mboxkey. If an attacker knew a folder name on the victim's account for which the victim had never issued an auth URL, they could forge a working URLAUTH token by computing an HMAC-SHA1 value with a predictable key, giving them read access to the mailbox. (URLAUTH is an obscure feature, meaning that the odds of any user actually being susceptible to this attack are very low. Perhaps no public clients use URLAUTH.)

It was found, that Cyrus IMAP recognized IMAP, LMTP, NNTP and POP3 protocol commands during plaintex to TLS session switch (by TLS protocol initialization). A remote attacker could use this flaw to insert plaintext, protocol relevant, commands into TLS protocol initialization messages, leading to execution of these commands during the ciphertext protocol phase, potentially allowing the attacker to steal the victim's mail or authentication credentials.

References: [1] http://www.kb.cert.org/vuls/id/555316 [2] http://bugzilla.cyrusimap.org/showbug.cgi?id=3423

Relevant upstream patch: [3] http://git.cyrusimap.org/cyrus-imapd/patch/?id=523a91a5e86c8b9a27a138f04a3e3f2d8786f162

An issue was discovered in cyrus-imapd in Cyrus IMAP through 3.12.2. There is an XAPPLEPUSHSERVICE folder existence oracle and push hijack. An authenticated IMAP user could probe for the existence of arbitrary mailboxes on other users' accounts via the XAPPLEPUSHSERVICE command and then create Apple Push Notification Service notifications for new mail in those mailboxes to their own APNS device. This did not leak any data about the content of mailboxes. Instead, a "mailbox has changed" notice would be pushed when the mailbox modseq changed.

An issue was discovered in cyrus-imapd in Cyrus IMAP through 3.12.2. There is heap exposure in nested MIME comment parsing. An authenticated IMAP user could craft an email message containing an RFC 822 comment ending with a backslash. When parsing the message, the server would read past the message's end in memory, and read into the heap, returning the read content to the user.

digestmd5.c in the CMU Cyrus Simple Authentication and Security Layer (SASL) library 2.1.18, and possibly other versions before 2.1.21, allows remote unauthenticated attackers to cause a denial of service (segmentation fault) via malformed inputs in DIGEST-MD5 negotiation.