CVE-2026-100891

HIGHPre-NVD 7.37.3—
EchelonGraph scoreHIGH confidence

Score 7.3 from GitHub Security Advisory published 2026-09-28. A secondary CVSS source baseline 7.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 5 sources updated this weekElevated
7.3EG
EchelonGraph verdictPlan mitigationSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 7.3Exploit: Elevated riskExposed services: Not assessed

No fix is confirmed yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for the fix.

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.

CVSS v3
7.3
EG Score
7.3HIGHhigh confidence
EG Risk
64
EG Risk 64/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity73% × 45%
Exploitation40% × 40%
Automatability100% × 15%
CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).
Action: No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.
EPSS PROB
0.3%
EPSS %ILE
19th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Attend at high (mission-essential systems).

No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.

Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 28, 2026

Last Modified

October 1, 2026

Advisory Details (1)

Auto-updated Sep 28, 2026
🔬 Proof of concept available. No patch confirmed yet.
generic🟡 PoC Available

OpenDMARC does not convert a U-label From domain to its A-label, so internationalised domains have DMARC bypassed entirely (OpenDMARC ≤ 1.4.2; latest version tested 2026-07-30)

https://weitongli.com/share/opendmarc-ulabel-not-converted.html

Vendor Advisories for CVE-2026-100891(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
opendmarc1.4.2-2 ... 1.4.2-5.1 (7 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
opendmarc1.4.2-5, 1.4.2-5.1
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
opendmarc1.4.2-5, 1.4.2-5.1
  • every version on: no fix on record
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 34× in last 7d / 38× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-10-05 07:02 UTCEG score recompute
  2. 2026-10-05 07:02 UTCGHSA enrichment
  3. 2026-10-04 23:21 UTCEPSS rescore
  4. 2026-10-04 18:23 UTCGHSA enrichment
  5. 2026-10-04 05:41 UTCGHSA enrichment
  6. 2026-10-03 17:03 UTCEG score recompute
  7. 2026-10-03 17:02 UTCGHSA enrichment
  8. 2026-10-03 14:25 UTCEPSS rescore
  9. 2026-10-03 04:24 UTCEG score recompute
  10. 2026-10-03 04:24 UTCGHSA enrichment
  11. 2026-10-02 15:45 UTCGHSA enrichment
  12. 2026-10-02 03:07 UTCEG score recompute
  13. 2026-10-02 03:07 UTCGHSA enrichment
  14. 2026-10-01 19:49 UTCEPSS rescore
  15. 2026-10-01 14:22 UTCEG score recompute
  16. 2026-10-01 14:22 UTCGHSA enrichment
  17. 2026-10-01 14:20 UTCNVD updateCVSS v4 → 5.5
  18. 2026-10-01 14:01 UTCEG score recompute
  19. 2026-10-01 14:01 UTCGHSA enrichment
  20. 2026-10-01 14:00 UTCMITRE cvelistV5CVSS v4 → 6.9
  21. 2026-10-01 06:44 UTCGHSA enrichment
  22. 2026-09-30 18:05 UTCEG score recompute
  23. 2026-09-30 18:04 UTCGHSA enrichment
  24. 2026-09-30 15:02 UTCEPSS rescore
  25. 2026-09-30 05:25 UTCGHSA enrichment
Show 13 more
  1. 2026-09-29 16:46 UTCEG score recompute
  2. 2026-09-29 16:46 UTCGHSA enrichment
  3. 2026-09-29 15:20 UTCEPSS rescore
  4. 2026-09-29 04:08 UTCEG score recompute
  5. 2026-09-29 04:08 UTCGHSA enrichment
  6. 2026-09-28 15:29 UTCGHSA enrichment
  7. 2026-09-28 13:59 UTCEG score recompute
  8. 2026-09-28 13:59 UTCGHSA enrichment
  9. 2026-09-28 13:50 UTCEPSS rescore
  10. 2026-09-28 01:20 UTCEG score recompute
  11. 2026-09-28 01:19 UTCNVD updateCVSS v4 → 5.5
  12. 2026-09-28 00:48 UTCEG score recompute
  13. 2026-09-28 00:47 UTCMITRE cvelistV5first tracked

Related CVEs(same product + same CWE)

Frequently asked(5)

What is CVE-2026-100891?
CVE-2026-100891 is a high vulnerability published on September 28, 2026. A vulnerability has been found in Trusted Domain Project OpenDMARC up to 1.4.2. Affected by this issue is the function opendmarcpolicyquerydmarc in the library libopendmarc/opendmarcpolicy.c of the component Internationalized Domain Name Handler. Such manipulation leads to encoding error. It is…
When was CVE-2026-100891 disclosed?
CVE-2026-100891 was first published on September 28, 2026, with the most recent update on October 1, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-100891 actively exploited?
CVE-2026-100891 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (19th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-100891?
CVE-2026-100891 has a CVSS base score of 7.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-100891?
No fix for CVE-2026-100891 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The vendor advisories EchelonGraph has for CVE-2026-100891 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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