CVE-2026-79590

MEDIUMPre-NVD 6.56.5—
EchelonGraph scoreHIGH confidence

Score 6.5 from GitHub Security Advisory published 2026-09-11. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — 3 sources updated this weekElevated
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.5Exploit: Elevated riskExposed: 0

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

A NULL pointer dereference vulnerability exists in the Prism parser component of mruby 4.0.0. An attacker can provide a specially crafted Ruby source file that triggers the parser to pass a NULL pointer to nonnull string handling functions, resulting in undefined behavior and application crash.

CVSS v3
6.5
EG Score
6.5(high)
EG Risk
45(Track)
EG Risk 45/100SSVC: 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
Severity65% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
28%
KEV
Not listed

Published

September 10, 2026

Last Modified

September 22, 2026

Advisory Details (2)

Auto-updated Sep 14, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit.
github_commit

commit c6866eed4ad5 (takumin/mruby)

Fix landed in takumin/mruby commit c6866eed4ad5 — awaiting tagged release

https://github.com/takumin/mruby/commit/c6866eed4ad5640b552ba79d16063e7ec70a0ac9
generic

[Bug]mruby-compiler/Prism parser passes NULL to nonnull string functions (UBSan undefined behavior, CWE-476) · Issue #7032 · mruby/mruby · GitHub

https://github.com/mruby/mruby/issues/7032

Vendor Advisories for CVE-2026-79590(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 20× in last 7d / 42× 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. 2026-09-24 23:28 UTCEG score recompute
  2. 2026-09-24 23:28 UTCGHSA enrichment
  3. 2026-09-24 14:04 UTCEPSS rescore
  4. 2026-09-23 21:52 UTCEG score recompute
  5. 2026-09-23 21:52 UTCGHSA enrichment
  6. 2026-09-23 17:54 UTCEPSS rescore
  7. 2026-09-22 20:16 UTCEG score recompute
  8. 2026-09-22 20:16 UTCGHSA enrichment
  9. 2026-09-22 16:01 UTCEPSS rescore
  10. 2026-09-22 06:36 UTCEG score recompute
  11. 2026-09-22 06:36 UTCGHSA enrichment
  12. 2026-09-21 21:09 UTCEPSS rescore
  13. 2026-09-21 05:00 UTCEG score recompute
  14. 2026-09-21 04:59 UTCGHSA enrichment
  15. 2026-09-20 20:16 UTCEPSS rescore
  16. 2026-09-20 03:07 UTCEG score recompute
  17. 2026-09-20 03:07 UTCGHSA enrichment
  18. 2026-09-19 01:30 UTCEG score recompute
  19. 2026-09-19 01:30 UTCGHSA enrichment
  20. 2026-09-18 19:28 UTCEPSS rescore
  21. 2026-09-17 23:54 UTCEG score recompute
  22. 2026-09-17 23:54 UTCGHSA enrichment
  23. 2026-09-16 21:47 UTCEG score recompute
  24. 2026-09-16 21:47 UTCGHSA enrichment
  25. 2026-09-16 14:08 UTCEPSS rescore
Show 17 more
  1. 2026-09-16 05:15 UTCEPSS rescore
  2. 2026-09-15 20:11 UTCEG score recompute
  3. 2026-09-15 20:11 UTCGHSA enrichment
  4. 2026-09-15 03:12 UTCEPSS rescore
  5. 2026-09-15 03:12 UTCEPSS rescore
  6. 2026-09-14 18:34 UTCEG score recompute
  7. 2026-09-14 18:34 UTCGHSA enrichment
  8. 2026-09-14 17:21 UTCEG score recompute▲ 6.50
  9. 2026-09-14 17:21 UTCGHSA enrichment
  10. 2026-09-14 17:21 UTCMITRE cvelistV5CVSS v3 → 6.5 · severity → MEDIUM
  11. 2026-09-13 19:35 UTCEG score recompute
  12. 2026-09-13 19:35 UTCGHSA enrichment
  13. 2026-09-11 14:53 UTCEPSS rescore
  14. 2026-09-11 14:53 UTCEPSS rescore
  15. 2026-09-10 22:18 UTCNVD update
  16. 2026-09-10 21:55 UTCEG score recompute
  17. 2026-09-10 21:54 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-79590?
CVE-2026-79590 is a medium vulnerability published on September 10, 2026. A NULL pointer dereference vulnerability exists in the Prism parser component of mruby 4.0.0. An attacker can provide a specially crafted Ruby source file that triggers the parser to pass a NULL pointer to nonnull string handling functions, resulting in undefined behavior and application crash.
When was CVE-2026-79590 disclosed?
CVE-2026-79590 was first published in the National Vulnerability Database on September 10, 2026, with the most recent update on September 22, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-79590 actively exploited?
CVE-2026-79590 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 72.2% of all scored CVEs.
What is the CVSS score of CVE-2026-79590?
CVE-2026-79590 has a CVSS v3.1 base score of 6.5 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-79590?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-79590, 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

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