Use After Free in Open-Xchange Gmbh Ox Dovecot Ce
CVE-2026-42007
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.
Vulnerability class: Use-After-Free
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H.
EPSS exploit prediction
EPSS: 0.003 (26.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 26th percentile — 26.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: +0.001
Affected products
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-42007?
- CVE-2026-42007 is a critical-severity vulnerability in Open-Xchange Gmbh Ox Dovecot Ce, classified under Use After Free. CVSS score: 9.1/10. Published 2026-08-28.
- How severe is CVE-2026-42007?
- Critical severity. CVSS v3 base score is 9.1 out of 10.