Read the docs
TI-2025-38045 Aliases CVE-2025-61600

Unbounded Memory Allocation in Stalwart IMAP parser

Priority MEDIUM 40CWE-400Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-400.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00562 46th percentileScored 2026-11-07
Fix Fixed stalwart (stalwartlabs): 0.13.4

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
stalwartlabsstalwartbefore 0.13.40.13.4Patch availableCNA
  • stalwart Vendorstalwartlabs Affected before 0.13.4 Fixed in 0.13.4 Patch available CNA

Remediation

  • Fix · CNA stalwart (stalwartlabs) Fixed in 0.13.4

Timeline

  1. 2026-10-02 Threatist record created from CVE-2025-61600

References

Other 3

  • TI-2024-23261 Stalwart Mail Server has privilege escalation by design CVSS 3.1CRITICAL 9.1
  • TI-2026-56046 Stalwart Mail Server through 0.16.19 Authorization Code Disclosure via Unvalidated OAuth redirect_uri CVSS 4.0HIGH 8.5
  • TI-2024-23253 Unprivileged Stalwart Mail Server user can read files as root CVSS 3.1MEDIUM 6.8
  • TI-2025-36687 Stalwart vulnerable to Memory Exhaustion via CalDAV Event Expansion CVSS 4.0HIGH 7.1

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences