CVE-2026-89133

MEDIUMNVD 5.35.3—
EchelonGraph scoreHIGH confidence

Score 5.3 from GitHub Security Advisory published 2026-09-27. NVD baseline CVSS 5.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 5 sources updated this week
5.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.1%CVSS: 5.3Exploit: None knownExposed services: Not assessed

An upstream fix is merged but not yet released — mitigate (WAF / firewall / segmentation) until the release ships, then apply it.

wolfSSL versions 5.9.2 and earlier contain a flaw in the X.509 certificate validation logic where it fails to properly enforce NameConstraints extensions when there is an unconstrained CA tier between a name-constrained intermediate CA and the leaf certificate. wolfSSL incorrectly accepted certificates for hostnames they shouldn't be allowed to cover, due to a chain-walking state-machine bug that resets the validation state when encountering an intermediate without NameConstraints, thereby bypassing cryptographic delegation controls. This defect exists in the default build configuration that makes use of certificates where name constraint extensions are used. Thanks to Jack Lloyd, PathDiff, and Ben Smyth for reporting the issue.

CVSS v3
5.3
EG Score
5.3MEDIUMhigh confidence
EG Risk
39
EG Risk 39/100CISA 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
Severity53% × 45%
Exploitation0% × 40%
Automatability100% × 15%
CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).
Action: An upstream fix is merged but not yet in a tagged release. 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 until it ships, then apply the release.
EPSS PROB
0.1%
EPSS %ILE
1st
KEV
Not listed

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

An upstream fix is merged but not yet in a tagged release. 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 until it ships, then apply the release.

Exploitation none (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

October 2, 2026

Advisory Details (1)

Auto-updated Sep 27, 2026
Upstream fix merged — awaiting tagged release. Sources: github_pr.
github_pr

Name Constraints cert chain walk

Fix merged in wolfSSL/wolfssl PR #10687 on 2026-07-01 — awaiting tagged release

https://github.com/wolfSSL/wolfssl/pull/10687

Vendor Advisories for CVE-2026-89133(2)

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 23× 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. 2026-10-03 19:40 UTCEG score recompute
  2. 2026-10-03 19:40 UTCVendor advisory
  3. 2026-10-03 19:40 UTCGHSA enrichment
  4. 2026-10-02 19:00 UTCEG score recompute▼ 1.00
  5. 2026-10-02 19:00 UTCVendor advisory
  6. 2026-10-02 19:00 UTCGHSA enrichment
  7. 2026-10-02 18:59 UTCNVD updateCVSS v3 → 5.3
  8. 2026-10-01 19:51 UTCEPSS rescore
  9. 2026-10-01 19:00 UTCVendor advisory
  10. 2026-10-01 19:00 UTCGHSA enrichment
  11. 2026-09-30 18:17 UTCEG score recompute
  12. 2026-09-30 18:17 UTCGHSA enrichment
  13. 2026-09-30 15:04 UTCEPSS rescore
  14. 2026-09-29 17:36 UTCEG score recompute
  15. 2026-09-29 17:36 UTCGHSA enrichment
  16. 2026-09-29 16:45 UTCEG score recompute
  17. 2026-09-29 16:45 UTCGHSA enrichment
  18. 2026-09-28 20:50 UTCEG score recompute
  19. 2026-09-28 20:50 UTCGHSA enrichment
  20. 2026-09-28 13:52 UTCEPSS rescore
  21. 2026-09-28 11:00 UTCEG score recompute
  22. 2026-09-28 11:00 UTCGHSA enrichment
  23. 2026-09-27 13:48 UTCEPSS rescore
  24. 2026-09-27 10:20 UTCEG score recompute
  25. 2026-09-27 09:35 UTCEG score recompute
Show 1 more
  1. 2026-09-27 09:35 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-89133?
CVE-2026-89133 is a medium vulnerability published on September 27, 2026. wolfSSL versions 5.9.2 and earlier contain a flaw in the X.509 certificate validation logic where it fails to properly enforce NameConstraints extensions when there is an unconstrained CA tier between a name-constrained intermediate CA and the leaf certificate. wolfSSL incorrectly accepted…
When was CVE-2026-89133 disclosed?
CVE-2026-89133 was first published on September 27, 2026, with the most recent update on October 2, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-89133 actively exploited?
CVE-2026-89133 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.1% probability of exploitation in the next 30 days (1st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-89133?
CVE-2026-89133 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2026-89133?
An upstream fix for CVE-2026-89133 has been merged but is not yet in a tagged release. Until it ships, restrict network exposure of the affected system or apply the vendor's mitigation, then update to the release that contains the fix. The vendor advisories EchelonGraph has for CVE-2026-89133 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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