# CVE-2026-101281: OpenDMARC improper authentication in SPF macro handler

Source: https://junglewise.ai/threats/cve-2026-101281-a-flaw-has-been-found-in-trusted-domain-project-opendmarc-up-to  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-29. Updated: 2026-09-29  
License: CC BY 4.0 with a link back

CVE-2026-101281 · Severity: high · CVSS 7.3 · Published 2026-09-29

OpenDMARC is a library that validates email authentication standards (DMARC and SPF) to prevent email spoofing. A flaw in the SPF macro handling function allows an attacker to bypass authentication checks remotely. This could enable email spoofing and allow malicious emails to pass authentication validation.

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-2026-101281 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-101281 being exploited in the wild.

**How severe is CVE-2026-101281?** High severity, with a CVSS score of 7.3, published 29 September 2026.

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

**Is there a fix for CVE-2026-101281?** A patch was published on 2026-09-29: Patch c48a74c758677fc5272a73eff15ffdbf8afda1a6 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-101281 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-101281?** 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

The opendmarc_sp2_find_mailfrom_domain function in libopendmarc/opendmarc_spf.c has improper handling of SPF macros, allowing authentication bypass through remote network attack. The vulnerability stems from incorrect macro substitution in SPF record processing. A patch (c48a74c758677fc5272a73eff15ffdbf8afda1a6) addresses the issue by fixing the ordering of environment variable setup for HELO and MAIL FROM domains.

## Affected products

- Trusted Domain Project OpenDMARC up to 1.4.2

## Timeline

- 2026-09-29: disclosed
- 2026-09-29: patched: Patch c48a74c758677fc5272a73eff15ffdbf8afda1a6

## References

- [https://github.com/trusteddomainproject/OpenDMARC/commit/c48a74c758677fc5272a73eff15ffdbf8afda1a6](https://github.com/trusteddomainproject/OpenDMARC/commit/c48a74c758677fc5272a73eff15ffdbf8afda1a6)
- [https://github.com/trusteddomainproject/OpenDMARC/issues/262](https://github.com/trusteddomainproject/OpenDMARC/issues/262)

## Related threats

- [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)
- [Trusted Domain Project OpenDMARC exception handling in DMARC policy parsing](https://junglewise.ai/threats/cve-2026-101016-a-vulnerability-has-been-found-in-trusted-domain-project)