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 a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.5Exploit: None knownExposed: 0

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

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
7.5(medium)
EG Risk
49(Track)
EG Risk 49/100SSVC: 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
Severity75% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
31%
KEV
Not listed

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 / 102× 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 134 total refreshes for this CVE.

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

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 in the National Vulnerability Database 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% probability of exploitation in the next 30 days, which ranks it in the top 68.9% of all 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?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-67991, 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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