CVE-2026-42007 Use after free in OX Dovecot CE
Authenticated attackers can trigger a use-after-free via Sieve scripts to cause memory corruption, potentially leading to arbitrary code execution or crashes.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-42007?
CVE-2026-42007 is a critical use after free vulnerability in Open-Xchange GmbH OX Dovecot CE, published on 28 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Weakness: CWE-416
Which versions are affected by CVE-2026-42007?
How do I fix CVE-2026-42007?
Upgrade to a fixed version.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-42007 being exploited?
There is no known exploitation of CVE-2026-42007 in the wild and no public exploit code.
Sources
Also known as ALPINE-CVE-2026-42007, AZL-98298, CLSA-2026-1792596933, CLSA-2026-1792753135, CLSA-2026-1792753365, CLSA-2026-1792764227 and 4 more.