CVE-2026-42007: open-xchange gmbh ox dovecot ce Use After Free

Vulnerability summary

CVE-2026-42007 is a critical (CVSS 9.1) Use After Free vulnerability in open-xchange gmbh ox dovecot ce. EPSS estimates a 0.34% chance of exploitation in the next 30 days, higher than 26.7% of scored vulnerabilities.

Timeline

1. 28-08-2026
   PublishedVulnerability first disclosed.
2. 28-08-2026
   Last modifiedVulnerability information updated.

Description

An attacker that has valid credentials can use a Sieve script with the editheader extension to trigger a use-after-free in the mail editing code, and to write memory contents beyond the intended buffer into the delivered mail. This causes memory leak and opportunity to do memory corruption during mail delivery, which can crash the delivery process and may allow execution of arbitrary code in the context of that process. Disable the Sieve editheader extension. Update to non-vulnerable version. No publicly available exploits are known.

• CWE-416Use After FreeThe product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.