Your RSA-2048 keys break in 2030. Find every one of them before attackers do.
🛡️
Not in CISA KEV
HIGH severity

CVE-2026-100891

HIGH

CVE-2026-100891 is a high-severity (CVSS 7.3) CWE-172 vulnerability. No vendor fix is recorded yet; mitigation options are listed below.

A vulnerability has been found in Trusted Domain Project OpenDMARC up to 1.4.2. Affected by this issue is the function opendmarc_policy_query_dmarc in the library libopendmarc/opendmarc_policy.c…

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 vulnerability has been found in Trusted Domain Project OpenDMARC up to 1.4.2. Affected by this issue is the function opendmarc_policy_query_dmarc in the library libopendmarc/opendmarc_policy.c of the component Internationalized Domain Name Handler. Such manipulation leads to encoding error. It is possible to launch the attack remotely. The exploit has been disclosed to the public and may be used. 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-2026-100891 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.

  3. Mitigate without a patch

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

A vulnerability has been found in Trusted Domain Project OpenDMARC up to 1.4.2. Affected by this issue is the function opendmarc_policy_query_dmarc in the library libopendmarc/opendmarc_policy.c of the component Internationalized Domain Name Handler. Such manipulation leads to encoding error. It is possible to launch the attack remotely. The exploit has been disclosed to the public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.
O3 Security · Impact-Aware SCA

Is CVE-2026-100891 in your dependencies?

Find it across , including transitive dependencies.

Scan my dependencies How O3 SCA works