# CVE-2026-101281: Trusted Domain Project OpenDMARC SPF Macro opendmarc_spf.c opendmarc_sp2_find_mailfrom_domain improper authentication

> Remote attackers can bypass authentication in OpenDMARC's SPF macro handler, potentially spoofing email domains.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 29 Sep 2026
- **Updated:** 1 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-101281, GHSA-fvpv-g9f4-87fc, UBUNTU-CVE-2026-101281

## What is CVE-2026-101281?

CVE-2026-101281 is a medium-severity authentication bypass vulnerability in Trusted Domain Project OpenDMARC, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A flaw has been found in Trusted Domain Project OpenDMARC up to 1.4.2. Affected by this vulnerability is the function opendmarc_sp2_find_mailfrom_domain of the file libopendmarc/opendmarc_spf.c of the component SPF Macro Handler. This manipulation causes improper authentication. The attack is possible to be carried out remotely. The exploit has been published and may be used. Patch name: c48a74c758677fc5272a73eff15ffdbf8afda1a6. Applying a patch is the recommended action to fix this issue.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2026-101281?


## How do I fix CVE-2026-101281?

No fix has been published for CVE-2026-101281 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-101281 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-101281 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-101281 and fix it if it is affected.

What it is: CVE-2026-101281 is a medium-severity authentication bypass vulnerability in Trusted Domain Project OpenDMARC, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-101281 exists.

Affected product: Trusted Domain Project OpenDMARC. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-101281/ (Markdown: https://insights.sbomify.com/CVE-2026-101281/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-101281
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-101281
- OSV: https://osv.dev/vulnerability/CVE-2026-101281

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-101281/
Summaries are generated and may contain mistakes; the official description above is the record.