CVE-2025-61600 Unbounded Memory Allocation in Stalwart IMAP parser
Remote attackers can exhaust server memory via the IMAP parser, causing a denial of service in Stalwart mail servers.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2025-61600?
CVE-2025-61600 is a high-severity denial of service vulnerability in stalwartlabs stalwart, published on 2 Oct 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2025-61600?
How do I fix CVE-2025-61600?
No fix has been published for CVE-2025-61600 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-61600 being exploited?
There is no known exploitation of CVE-2025-61600 in the wild and no public exploit code.
Sources
Also known as GHSA-8jqj-qj5p-v5rr.