Low [CVE-2026-52681] Denial of Service via Sieve script manipulation
This low-severity Red Hat Linux advisory covers CVE-2026-52681 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9.
Android app · Google Play
Monitor future Red Hat Linux CVEs from your phone.
Choose a whole vendor or a precise platform, then receive matching security advisories by phone notification, email, or both. Coverage follows 32 official vendor sources and 160+ reviewed platform categories.
Summary
Sieve CPU resource usage is tracked in the compiled script, so an attacker that has valid credentials can reset the accounting by repeatedly changing the active script. Compiled script files are also not removed when a script is deleted or renamed.
The configured Sieve CPU limit can be bypassed, allowing sustained CPU consumption, and the leftover files increase disk consumption. Both can cause degradation of service for mail delivery.
Monitor system for abnormal CPU usage and disk consumption. Update to non-vulnerable version.
No publicly available exploits are known. A flaw was found in dovecot.
This action prevents proper CPU resource accounting and leaves behind compiled script files, leading to sustained CPU and increased disk consumption. Red Hat severity: Low — CVSS 3.1 (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L).
Weakness: CWE-770. Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9.
Red Hat does not currently list a fixing RHSA for this CVE.
Affected products named by the advisory: Red Hat package: dovecot.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
Mitigation checklist
- Administrators can monitor system resources for abnormal CPU usage and disk consumption related to Dovecot Sieve processes. To prevent exploitation, if Sieve functionality is not required, it can be disabled by removing the `sieve` plugin from the `mail_plugins` setting in the Dovecot configuration. Disabling Sieve will impact user mail filtering capabilities. A restart of the Dovecot service is required for configuration changes to take effect.
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
Discussion(0)
No comments yet. Share field notes, upgrade gotchas, or questions — verify against the vendor advisory before acting on community advice.
Sign in to join the discussion.