Bulwark Webmail is a self-hosted webmail client for Stalwart Mail Server. Prior to 1.9.2, the unauthenticated POST /api/fetch-ical endpoint validates a caller-supplied hostname with one DNS lookup and then passes the URL to fetch, which performs a separate lookup for the socket connection. An attacker controlling authoritative DNS can return a public address during validation and then rebind the hostname to a loopback, private, link-local, or cloud metadata address for the connection, causing the server to return up to 10 MB of an internal HTTP or HTTPS response. The same check-then-fetch pattern also existed in authenticated JMAP login and TOTP token-exchange flows. This issue is fixed in version 1.9.2.

Stalwart is a mail and collaboration server. A denial-of-service vulnerability exists in Stalwart Mail Server versions 0.13.0 through 0.15.4 where accessing a specially crafted email containing malformed nested message/rfc822 MIME parts via IMAP or JMAP causes excessive CPU and memory consumption, potentially leading to an out-of-memory condition and server crash. The malformed structure causes the mail-parser crate to produce cyclical references in its parsed representation, which Stalwart then follows indefinitely. Version 0.15.5 contains a patch.

Stalwart is a mail and collaboration server. Versions 0.13.3 and below contain an unbounded memory allocation vulnerability in the IMAP protocol parser which allows remote attackers to exhaust server memory, potentially triggering the system's out-of-memory (OOM) killer and causing a denial of service. The CommandParser implementation enforces size limits on its dynamic buffer in most parsing states, but several state handlers omit these validation checks. This issue is fixed in version 0.13.4. A workaround for this issue is to implement rate limiting and connection monitoring at the network level, however this does not provide complete protection.

Stalwart is a mail and collaboration server. Starting in version 0.12.0 and prior to version 0.13.3, a memory exhaustion vulnerability exists in Stalwart's CalDAV implementation that allows authenticated attackers to cause denial-of-service by triggering unbounded memory consumption through recurring event expansion. An authenticated attacker can crash the Stalwart server by creating recurring events with large payloads and triggering their expansion through CalDAV REPORT requests. A single malicious request expanding 300 events with 1000-character descriptions can consume up to 2 GB of memory. The vulnerability exists in the ArchivedCalendarEventData.expand function, which processes CalDAV REPORT requests with event expansion. When a client requests recurring events in their expanded form using the <C:expand> element, the server stores all expanded event instances in memory without enforcing size limits. Users should upgrade to Stalwart version 0.13.3 or later to receive a fix. If immediate upgrading is not possible, implement memory limits at the container/system level; monitor server memory usage for unusual spikes; consider rate limiting CalDAV REPORT requests; and restrict CalDAV access to trusted users only.

Stalwart Mail Server is an open-source mail server. Prior to version 0.8.0, attackers who achieved Arbitrary Code Execution as the stalwart-mail user (including web interface admins) can gain complete root access to the system. Usually, system services are run as a separate user (not as root) to isolate an attacker with Arbitrary Code Execution to the current service. Therefore, other system services and the system itself remains protected in case of a successful attack. stalwart-mail runs as a separate user, but it can give itself full privileges again in a simple way, so this protection is practically ineffective. Server admins who handed out the admin credentials to the mail server, but didn't want to hand out complete root access to the system, as well as any attacked user when the attackers gained Arbitrary Code Execution using another vulnerability, may be vulnerable. Version 0.8.0 contains a patch for the issue.

Stalwart Mail Server is an open-source mail server. Prior to version 0.8.0, when using RUNASUSER, the specified user (and therefore, web interface admins) can read arbitrary files as root. This issue affects admins who have set up to run stalwart with RUNASUSER who handed out admin credentials to the mail server but expect these to only grant access according to the RUNASUSER and are attacked where the attackers managed to achieve Arbitrary Code Execution using another vulnerability. Version 0.8.0 contains a patch for the issue.