{"data":{"id":"bb5d5704-b353-47de-ba5f-04fa17b18834","title":"OpenAI’s GPT-5.5 is as Good as Mythos at Finding Security Vulnerabilities","summary":"The UK's AI Security Institute tested whether GPT-5.5 (OpenAI's model) could find security vulnerabilities as well as Claude Mythos, and found they perform comparably. A smaller, cheaper model also performed equally well, though it needs more scaffolding (additional structure and guidance provided by the person writing prompts to the AI).","solution":"N/A -- no mitigation discussed in source.","labels":["research","security"],"sourceUrl":"https://www.schneier.com/blog/archives/2026/05/openais-gpt-5-5-is-as-good-as-mythos-at-finding-security-vulnerabilities.html","publishedAt":"2026-05-13T11:03:03.000Z","cveId":null,"cweIds":null,"cvssScore":null,"cvssSeverity":null,"severity":"info","attackType":[],"issueType":"news","affectedPackages":null,"affectedVendors":["OpenAI","Anthropic"],"affectedVendorsRaw":["OpenAI","GPT-5.5","Claude Mythos","UK AI Security Institute"],"classifierModel":"claude-haiku-4-5-20251001","classifierPromptVersion":"v3","cvssVector":null,"attackVector":null,"attackComplexity":null,"privilegesRequired":null,"userInteraction":null,"exploitMaturity":null,"epssScore":null,"patchAvailable":null,"disclosureDate":"2026-05-13T11:03:03.000Z","capecIds":null,"crossRefCount":0,"attackSophistication":"moderate","impactType":null,"aiComponentTargeted":"model","llmSpecific":true,"classifierConfidence":0.75,"researchCategory":null,"atlasIds":null}}