CVE-2026-86813

MEDIUMPre-NVD 4.84.8—
EchelonGraph scoreHIGH confidence

Score 4.8 from GitHub Security Advisory published 2026-09-11. a secondary CVSS source baseline 4.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
4.8EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 4.8Exploit: None knownExposed: 0

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

The MetForm WordPress plugin before 4.1.9 does not properly neutralize newline characters in user-submitted values that are placed into notification email headers, allowing unauthenticated attackers to inject additional email headers, such as Bcc, into the emails the site sends when a submitted field value is configured to populate a header.

CVSS v3
4.8
EG Score
4.8(high)
EG Risk
22(Track)
EG Risk 22/100SSVC: Track

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
Severity48% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
5%
KEV
Not listed

Published

September 11, 2026

Last Modified

September 11, 2026

Advisory Details (1)

Auto-updated Sep 11, 2026
🔬 Proof of concept available. No patch confirmed yet.
generic🟡 PoC Available

MetForm < 4.1.9 – Unauthenticated Email Header Injection via Notification Reply-To | CVE 2026-86813 | Plugin Vulnerabilities

https://wpscan.com/vulnerability/afda2a26-b965-42cb-85a8-4a4d83ec026e/

Vendor Advisories for CVE-2026-86813(1)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 19× in last 7d / 26× 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. 2026-09-18 22:55 UTCEG score recompute
  2. 2026-09-18 22:55 UTCGHSA enrichment
  3. 2026-09-18 19:28 UTCEPSS rescore
  4. 2026-09-17 22:13 UTCEG score recompute
  5. 2026-09-17 22:13 UTCGHSA enrichment
  6. 2026-09-17 19:32 UTCEPSS rescore
  7. 2026-09-16 21:31 UTCEG score recompute
  8. 2026-09-16 21:31 UTCGHSA enrichment
  9. 2026-09-16 14:09 UTCEPSS rescore
  10. 2026-09-16 05:15 UTCEPSS rescore
  11. 2026-09-15 20:49 UTCEG score recompute
  12. 2026-09-15 20:49 UTCGHSA enrichment
  13. 2026-09-15 03:12 UTCEPSS rescore
  14. 2026-09-15 03:12 UTCEPSS rescore
  15. 2026-09-14 19:59 UTCGHSA enrichment
  16. 2026-09-13 19:17 UTCEG score recompute
  17. 2026-09-13 19:17 UTCGHSA enrichment
  18. 2026-09-12 18:35 UTCEG score recompute
  19. 2026-09-12 18:35 UTCGHSA enrichment
  20. 2026-09-11 17:53 UTCGHSA enrichment
  21. 2026-09-11 13:23 UTCEG score recompute
  22. 2026-09-11 13:23 UTCGHSA enrichment
  23. 2026-09-11 12:20 UTCEG score recompute
  24. 2026-09-11 11:26 UTCEG score recompute
  25. 2026-09-11 11:00 UTCEG score recompute
Show 1 more
  1. 2026-09-11 10:59 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-86813?
CVE-2026-86813 is a medium vulnerability published on September 11, 2026. The MetForm WordPress plugin before 4.1.9 does not properly neutralize newline characters in user-submitted values that are placed into notification email headers, allowing unauthenticated attackers to inject additional email headers, such as Bcc, into the emails the site sends when a submitted…
When was CVE-2026-86813 disclosed?
CVE-2026-86813 was first published in the National Vulnerability Database on September 11, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-86813 actively exploited?
CVE-2026-86813 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 95.0% of all scored CVEs.
What is the CVSS score of CVE-2026-86813?
CVE-2026-86813 has a CVSS v3 base score of 4.8 (NVD).
How do I remediate CVE-2026-86813?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-86813, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-86813

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