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HIGH severity

CVE-2026-100888

HIGH

CVE-2026-100888 is a high-severity (CVSS 7.3) Buffer Overflow vulnerability. No vendor fix is recorded yet; mitigation options are listed below.

A weakness has been identified in Trusted Domain Project OpenDKIM up to 2.11.0. This affects the function dkim_canon_selecthdrs of the file libopendkim/dkim-canon.c of the component…

Published
Sep 28, 2026
Updated
Sep 28, 2026
Affected
—
Patched
—
Exploits
None indexed
Exploitation data as of Sep 28, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Description

A weakness has been identified in Trusted Domain Project OpenDKIM up to 2.11.0. This affects the function dkim_canon_selecthdrs of the file libopendkim/dkim-canon.c of the component DKIM Signature Header Selection. Executing a manipulation of the argument h can lead to out-of-bounds write. The attack can be executed remotely. The exploit has been made available to the public and could be used for attacks. The vendor was contacted early about this disclosure but did not respond in any way.

Detection & mitigation playbook

Vulnerability
  1. Detect

    Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).

  2. Remediation status

    No fixed release is recorded for CVE-2026-100888 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.

  3. Mitigate without a patch

    Constrain what reaches the vulnerable code: limit the size and shape of untrusted input, isolate the affected component in a sandboxed or least-privileged process, and enable the platform's memory-safety mitigations (ASLR, stack protector, hardened allocator) so an out-of-bounds access is more likely to fail closed than to be exploitable.

Frequently Asked Questions

A weakness has been identified in Trusted Domain Project OpenDKIM up to 2.11.0. This affects the function dkim_canon_selecthdrs of the file libopendkim/dkim-canon.c of the component DKIM Signature Header Selection. Executing a manipulation of the argument h can lead to out-of-bounds write. The attack can be executed remotely. The exploit has been made available to the public and could be used for attacks. The vendor was contacted early about this disclosure but did not respond in any way.
O3 Security · Impact-Aware SCA

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CVE-2026-100888: Memory Corruption | O3 Security