OX Dovecot Pro: Use After Free
CVE-2026-42007 is a critical-severity use after free vulnerability in OX Dovecot Pro from Open-Xchange, with a CVSS 3.1 base score of 9.1 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. The record lists versions 2.3.22.2, 3.0.7, 3.1.6 as the first without the flaw, so updating OX Dovecot Pro to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.34% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update OX Dovecot Pro to 2.3.22.2 or 3.0.7 or 3.1.6, whichever matches your release line, or a later version.
- Update OX Dovecot CE to 2.4.5 or a later version.
- Read the advisory on documentation.open-xchange.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Open-Xchange | OX Dovecot Pro | 2.3.0 up to, but not including, 2.3.22.2; 3.0.0 up to, but not including, 3.0.7; 3.1.0 up to, but not including, 3.1.6 | 2.3.22.2, 3.0.7, 3.1.6 |
| Open-Xchange | OX Dovecot CE | 2.3.0 up to, but not including, 2.4.5 | 2.4.5 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- LowSome restricted data can be read.
- Integrity
- LowLimited modification of data is possible.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H. Scored by CNA (open-xchange.com).
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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use After Free
The 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.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Other vulnerabilities in OX Dovecot Pro
- 7.4 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 9.1 Critical severity
- 7.5 High severity
Recent Use After Free vulnerabilities
- 8.2 High severity
- 7.1 High severity
- 7.8 High severity
- 7.8 High severity
- 9.6 Critical severity
- 9.6 Critical severity
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