CVE-2026-100888

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 weakness has been identified in Trusted Domain Project OpenDKIM up to 2.11.0. This affects the function dkim_canon_selecthdrs of the file libopendkim/dkim-canon.c of the component DKIM Signature Header Selection. Executing a manipulation of the argument h can lead to out-of-bounds write. The attack can be executed remotely. The exploit has been made available to the public and could be used for attacks. 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 27, 2026

Last Modified

September 30, 2026

Advisory Details (1)

Auto-updated Sep 27, 2026
🔬 Proof of concept available. No patch confirmed yet.
generic🟡 PoC Available

OpenDKIM heap out-of-bounds write in dkim_canon_selecthdrs() via the DKIM-Signature h= tag (OpenDKIM ≤ 2.11.0; latest version tested 2026-07-30)

https://weitongli.com/share/opendkim-h-tag-oob-write.html

Vendor Advisories for CVE-2026-100888(1)

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

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 36× in last 7d / 36× 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. 2026-10-04 03:28 UTCGHSA enrichment
  2. 2026-10-03 14:49 UTCEG score recompute
  3. 2026-10-03 14:49 UTCGHSA enrichment
  4. 2026-10-03 14:25 UTCEPSS rescore
  5. 2026-10-03 02:11 UTCEG score recompute
  6. 2026-10-03 02:11 UTCGHSA enrichment
  7. 2026-10-02 13:32 UTCGHSA enrichment
  8. 2026-10-02 00:53 UTCGHSA enrichment
  9. 2026-10-02 00:53 UTCEG score recompute
  10. 2026-10-02 00:52 UTCGHSA enrichment
  11. 2026-10-01 19:49 UTCEPSS rescore
  12. 2026-10-01 12:10 UTCGHSA enrichment
  13. 2026-09-30 23:31 UTCEG score recompute
  14. 2026-09-30 23:31 UTCGHSA enrichment
  15. 2026-09-30 23:29 UTCNVD updateCVSS v4 → 5.5
  16. 2026-09-30 22:26 UTCEG score recompute
  17. 2026-09-30 22:26 UTCGHSA enrichment
  18. 2026-09-30 22:25 UTCMITRE cvelistV5CVSS v4 → 6.9
  19. 2026-09-30 18:05 UTCEG score recompute
  20. 2026-09-30 18:05 UTCGHSA enrichment
  21. 2026-09-30 15:02 UTCEPSS rescore
  22. 2026-09-30 05:25 UTCGHSA enrichment
  23. 2026-09-29 16:46 UTCEG score recompute
  24. 2026-09-29 16:46 UTCGHSA enrichment
  25. 2026-09-29 15:20 UTCEPSS rescore
Show 11 more
  1. 2026-09-29 04:08 UTCEG score recompute
  2. 2026-09-29 04:08 UTCGHSA enrichment
  3. 2026-09-28 15:29 UTCEG score recompute
  4. 2026-09-28 15:29 UTCGHSA enrichment
  5. 2026-09-28 13:50 UTCEPSS rescore
  6. 2026-09-28 12:57 UTCEG score recompute
  7. 2026-09-28 12:57 UTCGHSA enrichment
  8. 2026-09-28 00:18 UTCEG score recompute
  9. 2026-09-28 00:17 UTCNVD updateCVSS v4 → 5.5
  10. 2026-09-27 23:34 UTCEG score recompute
  11. 2026-09-27 23:33 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-100888?
CVE-2026-100888 is a high vulnerability published on September 27, 2026. A weakness has been identified in Trusted Domain Project OpenDKIM up to 2.11.0. This affects the function dkimcanonselecthdrs of the file libopendkim/dkim-canon.c of the component DKIM Signature Header Selection. Executing a manipulation of the argument h can lead to out-of-bounds write. The attack…
When was CVE-2026-100888 disclosed?
CVE-2026-100888 was first published on September 27, 2026, with the most recent update on September 30, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-100888 actively exploited?
CVE-2026-100888 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-2026-100888?
CVE-2026-100888 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-2026-100888?
No fix for CVE-2026-100888 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-2026-100888 are linked in the Vendor Advisories panel on this page.

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