CVE-2026-67991

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-08-13. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — 3 sources updated this week
7.5EG
EchelonGraph verdictPlan mitigationSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 7.5Exploit: None knownExposed services: Not assessed

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

crmne/ruby_llm at commit fa6f279847d6d7027814539d9c0dfc3bbdfd2a83 contains a polynomial-time regular expression denial-of-service condition in RubyLLM::Utils.underscore on Ruby 3.1.x. A very long crafted class, agent, or tool name can cause excessive CPU consumption and a denial of service.

CVSS v3
7.5
EG Score
7.5HIGHmedium confidence
EG Risk
49
EG Risk 49/100CISA 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
Severity75% × 45%
Exploitation1% × 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
0.5%
EPSS %ILE
41st
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 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

August 13, 2026

Last Modified

September 8, 2026

Advisory Details (3)

Auto-updated Aug 13, 2026
No patch confirmed yet.
generic

Public reference for CVE-2026-67991 · GitHub

https://gist.github.com/Zykis1024/9f2d68fa3fd4e3a0ab83063bbe61a8e2
generic

ruby_llm/lib/ruby_llm/utils.rb at fa6f279847d6d7027814539d9c0dfc3bbdfd2a83 · crmne/ruby_llm · GitHub

https://github.com/crmne/ruby_llm/blob/fa6f279847d6d7027814539d9c0dfc3bbdfd2a83/lib/ruby_llm/utils.rb#L13
generic

GitHub - crmne/ruby_llm: One delightful Ruby framework for every major AI provider. Build AI agents, chatbots, RAG apps, and multimodal workflows in beautiful, expressive code. · GitHub

https://github.com/crmne/ruby_llm

Vendor Advisories for CVE-2026-67991(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 21× in last 7d / 90× 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.

Showing the most recent 100 of 177 total refreshes for this CVE.

  1. 2026-10-04 23:22 UTCEPSS rescore
  2. 2026-10-04 22:26 UTCGHSA enrichment
  3. 2026-10-04 08:52 UTCGHSA enrichment
  4. 2026-10-03 19:54 UTCEG score recompute
  5. 2026-10-03 19:54 UTCGHSA enrichment
  6. 2026-10-03 14:26 UTCEPSS rescore
  7. 2026-10-02 21:56 UTCEG score recompute
  8. 2026-10-02 21:56 UTCGHSA enrichment
  9. 2026-10-02 17:56 UTCEPSS rescore
  10. 2026-10-02 08:07 UTCEG score recompute
  11. 2026-10-02 08:07 UTCGHSA enrichment
  12. 2026-10-01 19:50 UTCEPSS rescore
  13. 2026-10-01 10:48 UTCGHSA enrichment
  14. 2026-09-30 21:52 UTCEG score recompute
  15. 2026-09-30 21:52 UTCGHSA enrichment
  16. 2026-09-30 15:03 UTCEPSS rescore
  17. 2026-09-29 04:18 UTCEG score recompute
  18. 2026-09-29 04:18 UTCGHSA enrichment
  19. 2026-09-28 14:16 UTCEG score recompute
  20. 2026-09-28 14:16 UTCGHSA enrichment
  21. 2026-09-28 13:52 UTCEPSS rescore
  22. 2026-09-28 01:10 UTCEG score recompute
  23. 2026-09-28 01:10 UTCGHSA enrichment
  24. 2026-09-27 13:48 UTCEPSS rescore
  25. 2026-09-27 09:50 UTCEG score recompute
Show 75 more
  1. 2026-09-27 09:50 UTCGHSA enrichment
  2. 2026-09-26 15:59 UTCEPSS rescore
  3. 2026-09-25 03:38 UTCEG score recompute
  4. 2026-09-25 03:38 UTCGHSA enrichment
  5. 2026-09-24 05:38 UTCEG score recompute
  6. 2026-09-24 05:38 UTCGHSA enrichment
  7. 2026-09-23 17:54 UTCEPSS rescore
  8. 2026-09-23 16:44 UTCGHSA enrichment
  9. 2026-09-23 03:51 UTCEG score recompute
  10. 2026-09-23 03:51 UTCGHSA enrichment
  11. 2026-09-22 14:57 UTCGHSA enrichment
  12. 2026-09-22 02:03 UTCEG score recompute
  13. 2026-09-22 02:03 UTCGHSA enrichment
  14. 2026-09-21 13:08 UTCGHSA enrichment
  15. 2026-09-21 00:14 UTCEG score recompute
  16. 2026-09-21 00:14 UTCGHSA enrichment
  17. 2026-09-20 20:16 UTCEPSS rescore
  18. 2026-09-20 10:11 UTCGHSA enrichment
  19. 2026-09-19 19:01 UTCEG score recompute
  20. 2026-09-19 19:00 UTCGHSA enrichment
  21. 2026-09-19 05:58 UTCEG score recompute
  22. 2026-09-19 05:58 UTCGHSA enrichment
  23. 2026-09-18 19:28 UTCEPSS rescore
  24. 2026-09-18 16:56 UTCGHSA enrichment
  25. 2026-09-18 02:37 UTCEG score recompute
  26. 2026-09-18 02:37 UTCGHSA enrichment
  27. 2026-09-17 13:43 UTCGHSA enrichment
  28. 2026-09-17 00:15 UTCEG score recompute
  29. 2026-09-17 00:15 UTCGHSA enrichment
  30. 2026-09-16 14:08 UTCEPSS rescore
  31. 2026-09-16 05:15 UTCEPSS rescore
  32. 2026-09-16 02:01 UTCGHSA enrichment
  33. 2026-09-15 13:07 UTCEG score recompute
  34. 2026-09-15 13:07 UTCGHSA enrichment
  35. 2026-09-14 21:55 UTCGHSA enrichment
  36. 2026-09-14 08:58 UTCGHSA enrichment
  37. 2026-09-13 20:04 UTCEG score recompute
  38. 2026-09-13 20:04 UTCGHSA enrichment
  39. 2026-09-13 07:09 UTCGHSA enrichment
  40. 2026-09-12 18:16 UTCEG score recompute
  41. 2026-09-12 18:16 UTCGHSA enrichment
  42. 2026-09-12 05:22 UTCGHSA enrichment
  43. 2026-09-11 16:28 UTCEG score recompute
  44. 2026-09-11 16:28 UTCGHSA enrichment
  45. 2026-09-11 14:53 UTCEPSS rescore
  46. 2026-09-11 09:37 UTCEPSS rescore
  47. 2026-09-11 03:34 UTCGHSA enrichment
  48. 2026-09-10 14:40 UTCEG score recompute
  49. 2026-09-10 14:40 UTCGHSA enrichment
  50. 2026-09-10 01:46 UTCGHSA enrichment
  51. 2026-09-09 09:00 UTCEG score recompute
  52. 2026-09-09 09:00 UTCGHSA enrichment
  53. 2026-09-08 22:01 UTCEPSS rescore
  54. 2026-09-08 20:06 UTCGHSA enrichment
  55. 2026-09-08 06:30 UTCGHSA enrichment
  56. 2026-09-07 16:39 UTCEG score recompute
  57. 2026-09-07 16:39 UTCGHSA enrichment
  58. 2026-09-07 16:01 UTCEPSS rescore
  59. 2026-09-06 21:29 UTCEG score recompute
  60. 2026-09-06 21:29 UTCGHSA enrichment
  61. 2026-09-06 13:47 UTCEPSS rescore
  62. 2026-09-06 08:34 UTCGHSA enrichment
  63. 2026-09-05 19:41 UTCEG score recompute
  64. 2026-09-05 19:41 UTCGHSA enrichment
  65. 2026-09-05 15:31 UTCEPSS rescore
  66. 2026-09-05 06:47 UTCGHSA enrichment
  67. 2026-09-04 17:28 UTCGHSA enrichment
  68. 2026-09-04 16:44 UTCGHSA enrichment
  69. 2026-09-04 14:30 UTCEG score recompute
  70. 2026-09-04 14:30 UTCGHSA enrichment
  71. 2026-09-04 05:07 UTCEPSS rescore
  72. 2026-09-04 01:35 UTCGHSA enrichment
  73. 2026-09-03 12:40 UTCGHSA enrichment
  74. 2026-09-02 23:24 UTCEG score recompute
  75. 2026-09-02 23:24 UTCGHSA enrichment

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-67991?
CVE-2026-67991 is a high vulnerability published on August 13, 2026. crmne/ruby_llm at commit fa6f279847d6d7027814539d9c0dfc3bbdfd2a83 contains a polynomial-time regular expression denial-of-service condition in RubyLLM::Utils.underscore on Ruby 3.1.x. A very long crafted class, agent, or tool name can cause excessive CPU consumption and a denial of service.
When was CVE-2026-67991 disclosed?
CVE-2026-67991 was first published on August 13, 2026, with the most recent update on September 8, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-67991 actively exploited?
CVE-2026-67991 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (41st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-67991?
CVE-2026-67991 has a CVSS v3.1 base score of 7.5 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-67991?
No fix for CVE-2026-67991 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-2026-67991 are linked in the Vendor Advisories panel on this page.

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