Security advisory

{
  "id": "3eb037befd3eb067c37343ffc35f6b93ae4ba44c957f23c394159de7a969bc4d",
  "url": "https://osv.dev/vulnerability/CVE-2026-67991",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2026-67991",
    "summary": "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.",
    "evidence": "osv:CVE-2026-67991",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-67991",
      "aliases": [
        "CVE-2026-67991"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/crmne/ruby_llm",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "9d75b033d7d00c4e1baa9b0afb4828faa8bd6602"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "last_affected": "fa6f279847d6d7027814539d9c0dfc3bbdfd2a83"
                      }
                    ],
                    "source": "DESCRIPTION"
                  },
                  {
                    "range": [
                      {
                        "fixed": "9d75b033d7d00c4e1baa9b0afb4828faa8bd6602"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "1.16.0",
            "1.15.0",
            "1.14.1",
            "1.14.0",
            "1.13.2",
            "1.13.1",
            "1.13.0",
            "1.12.1",
            "1.12.0",
            "1.11.0",
            "1.10.0",
            "1.9.2",
            "1.9.1",
            "1.9.0",
            "1.8.2",
            "1.8.1",
            "1.8.0",
            "1.7.1",
            "1.7.0",
            "1.6.4",
            "1.6.3",
            "1.6.2",
            "1.6.1",
            "1.6.0",
            "1.5.1",
            "1.5.0",
            "1.4.0",
            "1.3.1",
            "1.3.0",
            "1.3.0rc1",
            "1.2.0",
            "1.1.2",
            "1.1.1",
            "1.1.0",
            "1.1.0rc2",
            "1.1.0rc1",
            "1.0.1",
            "1.0.0",
            "0.1.0.pre42"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-67991.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:39.522033323Z",
      "provider": "osv",
      "references": [
        "https://gist.github.com/Zykis1024/9f2d68fa3fd4e3a0ab83063bbe61a8e2",
        "https://github.com/crmne/ruby_llm/blob/fa6f279847d6d7027814539d9c0dfc3bbdfd2a83/lib/ruby_llm/utils.rb#L13",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/67xxx/CVE-2026-67991.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-67991",
        "https://github.com/crmne/ruby_llm/commit/9d75b033d7d00c4e1baa9b0afb4828faa8bd6602",
        "https://github.com/crmne/ruby_llm"
      ],
      "provider_metadata": {
        "cna_assigner": "mitre",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/67xxx/CVE-2026-67991.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-67991",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 507025,
  "published_at": "2026-08-13T00:00:00+00:00"
}