Is CVE-2026-100889 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-100889 being exploited in the wild.

How severe is CVE-2026-100889?

High severity, with a CVSS score of 7.3, published 28 September 2026.

Which products and versions are affected?

Trusted Domain Project OpenDKIM up to 2.11.0.

Is there a fix for CVE-2026-100889?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-100889 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-100889?

Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-100889: Trusted Domain Project OpenDKIM off-by-one in decoder

CVE-2026-100889 · Severity: high · CVSS 7.3 · Published 2026-09-28

OpenDKIM is an implementation of DKIM (DomainKeys Identified Mail) used to authenticate email messages. A decoding flaw in the quoted-printable decoder can be exploited remotely, potentially allowing an attacker to corrupt email authentication processing or cause denial of service. The vulnerability affects versions up to 2.11.0 and is now publicly exploited.

Quick answers

Is CVE-2026-100889 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-100889 being exploited in the wild.
How severe is CVE-2026-100889?: High severity, with a CVSS score of 7.3, published 28 September 2026.
Which products and versions are affected?: Trusted Domain Project OpenDKIM up to 2.11.0.
Is there a fix for CVE-2026-100889?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-100889 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-100889?: Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

An off-by-one error exists in the dkim_qp_decode function in util.c, which handles quoted-printable decoding in the OpenDKIM decoder component. The vulnerability can be triggered remotely via malformed email input without authentication. A successful exploit could lead to memory corruption, authentication bypass, or service disruption.

Affected products

Trusted Domain Project OpenDKIM up to 2.11.0

Timeline

2026-09-28: disclosed
other: Exploit is public and in active use; vendor did not respond to early disclosure notification

References

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