How severe is CVE-2026-100891?

CVE-2026-100891 has a CVSS 3.x base score of 7.3, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.

Is CVE-2026-100891 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (20th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-100891?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2026-100891 published?

CVE-2026-100891 was published on 2026-09-28 and last updated on 2026-10-01.

CVE-2026-100891

CVE-2026-100891 is a high-severity vulnerability with a CVSS 3.x base score of 7.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-172.

Key facts

Severity: High (CVSS 3.x base score 7.3)
CVSS v2: 7.5
CVSS v4: 5.5
EPSS exploit prediction: 0% (20th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-172
Published: 2026-09-28
Last modified: 2026-10-01

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.

Frequently asked questions

What is CVE-2026-100891?: 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.
How severe is CVE-2026-100891?: CVE-2026-100891 has a CVSS 3.x base score of 7.3, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.
Is CVE-2026-100891 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (20th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-100891?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-100891 published?: CVE-2026-100891 was published on 2026-09-28 and last updated on 2026-10-01.

References

Other CWE-172 vulnerabilities

CVE-2019-10160 — Critical (CVSS 9.8): A security regression of CVE-2019-9636 was discovered in python since commit d537ab0ff9767ef024f26246899728f0116b1ec3…
CVE-2018-3777 — Critical (CVSS 9.8): Insufficient URI encoding in restforce before 3.0.0 allows attacker to inject arbitrary parameters into Salesforce API…
CVE-2016-6691 — Critical (CVSS 9.8): service/jni/com_android_server_wifi_Gbk2Utf.cpp in the Qualcomm Wi-Fi gbk2utf module in Android before 2016-10-05…
CVE-2025-27110 — High (CVSS 7.5): Libmodsecurity is one component of the ModSecurity v3 project. The library codebase serves as an interface to…
CVE-2026-48784 — Medium (CVSS 6.1): Symfony is a PHP framework for web and console applications and a set of reusable PHP components. Prior to 5.4.53,…
CVE-2026-106122 — Medium (CVSS 6.0): The RabbitMQ Java client library allows Java and JVM-based applications to connect to and interact with RabbitMQ nodes.…

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