# CVE-2026-100890: OpenDMARC null pointer dereference in SPF parser

Source: https://junglewise.ai/threats/cve-2026-100890-a-flaw-has-been-found-in-trusted-domain-project-opendmarc-up-to  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-28. Updated: 2026-09-28  
License: CC BY 4.0 with a link back

CVE-2026-100890 · Severity: medium · CVSS 5.3 · Published 2026-09-28

OpenDMARC is an open-source email authentication library used to validate DMARC, SPF, and DKIM email signatures. A null pointer dereference vulnerability in the SPF parser allows an attacker to send a malicious email that crashes the mail processing service, causing a denial of service. The vulnerability can be triggered remotely without authentication.

Technologies: [Trusted Domain Project OpenDMARC](https://junglewise.ai/threats/technologies/opendmarc). Vendors: [Trusted Domain Project](https://junglewise.ai/threats/vendors/trusted-domain-project).

## Quick answers

**Is CVE-2026-100890 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-100890 being exploited in the wild.

**How severe is CVE-2026-100890?** Medium severity, with a CVSS score of 5.3, published 28 September 2026.

**Which products and versions are affected?** Trusted Domain Project OpenDMARC up to 1.4.2.

**Is there a fix for CVE-2026-100890?** 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-2026-100890 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-100890?** Check whether you run Trusted Domain Project OpenDMARC at an affected version. 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

A null pointer dereference exists in the opendmarc_spf_ipv6_explode function in libopendmarc/opendmarc_spf.c when processing SPF records with malformed IPv6 addresses. An attacker can craft an email with a specially formatted SPF record to trigger a null pointer dereference in the affected function, causing the application to crash. This is a remote, unauthenticated attack requiring only the ability to send email or DNS replies.

## Affected products

- Trusted Domain Project OpenDMARC up to 1.4.2

## Timeline

- 2026-09-28: disclosed

## References

- [https://vuldb.com/cve/CVE-2026-100890](https://vuldb.com/cve/CVE-2026-100890)
- [https://vuldb.com/submit/917188](https://vuldb.com/submit/917188)

## Related threats

- [OpenDMARC improper authentication in SPF macro handler](https://junglewise.ai/threats/cve-2026-101281-a-flaw-has-been-found-in-trusted-domain-project-opendmarc-up-to)
- [Trusted Domain Project OpenDMARC authentication bypass in Multi-Record Set Handler](https://junglewise.ai/threats/cve-2026-101280-a-vulnerability-was-detected-in-trusted-domain-project-opendmarc)
- [Trusted Domain Project OpenDMARC integer overflow in DMARC parser](https://junglewise.ai/threats/cve-2026-101279-a-security-vulnerability-has-been-detected-in-trusted-domain)
- [Trusted Domain Project OpenDMARC origin validation error in PSL Wildcard Handler](https://junglewise.ai/threats/cve-2026-101278-a-weakness-has-been-identified-in-trusted-domain-project)
- [Trusted Domain Project OpenDMARC exception handling in strcasecmp](https://junglewise.ai/threats/cve-2026-101017-a-vulnerability-was-found-in-trusted-domain-project-opendmarc-up)