CVE-2026-42007

dovecot: Dovecot: Arbitrary Code Execution via Sieve editheader use-after-free

Published Aug 28, 2026 CVSS 3.1 · 9.1 Critical EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4873-1 dovecot security update
Debian DSA Debian DSA DSA-6526-1 dovecot security update
History
Type Values Removed Values Added
First Time appeared Open-xchange
Open-xchange ox Dovecot Ce
Open-xchange ox Dovecot Pro
Vendors & Products Open-xchange
Open-xchange ox Dovecot Ce
Open-xchange ox Dovecot Pro
Type Values Removed Values Added
Title Use-After-Free in OX Dovecot Sieve Editheader Extension Allows Potential Code Execution dovecot: Dovecot: Arbitrary Code Execution via Sieve editheader use-after-free
Weaknesses CWE-825
References
Metrics threat_severity

None

threat_severity

Important

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Title Use-After-Free in OX Dovecot Sieve Editheader Extension Allows Potential Code Execution
Type Values Removed Values Added
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.
Weaknesses CWE-416
References
Metrics cvssV3_1

{'score': 9.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
OX
Published
Updated
Aug 28, 2026, 3:54 PM
Reserved
Apr 23, 2026, 11:15 AM
Status
Deferred
Published
Aug 28, 2026, 12:16 PM
Modified
Sep 3, 2026, 6:13 PM
Severity
Important
Public date
Aug 28, 2026, 10:12 AM