{"data":{"id":"738aae14-d42a-4324-8aff-bed6d5100241","title":"StealthyPoison: Manipulating LLM Agent Behavior through Procedural Poisoning of Third-Party Skills","summary":"StealthyPoison is a procedural poisoning attack that corrupts the decision-critical rules of a third-party agent skill while keeping its advertised functionality, so tasks fail without overt malicious instructions. The attack builds reusable poisoned procedures from a public skill using a surrogate agent, and augments retrieval metadata to improve placement. Evaluated on 566 target skills and 5,244 requests against more than 26,000 registry entries, it raised top-1 poisoned-skill placement by 13.6% relative to HotFlip and GCG, and most payloads evaded detection by SkillSpector and GPT-5.4-mini.","solution":"N/A -- no mitigation discussed in source.","labels":["security","research"],"sourceUrl":"https://arxiv.org/abs/2611.12155v1","publishedAt":"2026-11-09T10:05:07.000Z","cveId":null,"cweIds":null,"cvssScore":null,"cvssSeverity":null,"severity":"info","attackType":["supply_chain","other"],"issueType":"research","affectedPackages":null,"affectedPackageNames":null,"affectedPackageRefs":null,"affectedVendors":["Anthropic","OpenAI"],"affectedVendorsRaw":["Claude Code","Opus 4.8","GPT-5.4-mini","Claude"],"classifierModel":"claude-haiku-5-5","classifierPromptVersion":"v4","summaryPromptVersion":"v2","headline":null,"headlinePromptVersion":null,"cvssVector":null,"attackVector":null,"attackComplexity":null,"privilegesRequired":null,"userInteraction":null,"exploitMaturity":null,"epssScore":null,"epssCheckedAt":null,"kevDateAdded":null,"advisoryAliases":null,"affectedPackagesSource":null,"affectedPackagesCheckedAt":null,"patchAvailable":null,"disclosureDate":"2026-11-09T10:05:07.000Z","fixReleasedAt":null,"daysToFix":null,"fixCheckedAt":null,"capecIds":null,"crossRefCount":0,"attackSophistication":"advanced","impactType":["integrity","safety"],"aiComponentTargeted":"agent","llmSpecific":true,"classifierConfidence":0.95,"researchCategory":"preprint","atlasIds":["AML.T0010"]}}