{"id":"CVE-2026-107288","summary":"Pydantic AI: web_fetch_tool blocked_domains bypass via a hostname the resolver normalizes differently","details":"Pydantic AI is a Python agent framework for building applications and workflows with Generative AI. From 1.77.0 until 1.107.6 and 2.44.0, the local web_fetch_tool and the WebFetch local fallback compare blocked_domains entries with a URL hostname before both values are normalized to the form used by getaddrinfo. An attacker-influenced model can use an equivalent IDNA spelling, non-ASCII label separator, case variation, or trailing root label that resolves to a blocked host but does not match the configured string, causing the application to fetch that host with its own privileges. allowed_domains fails closed for unmatched spellings, and private-IP and cloud-metadata protections remain effective. This issue is fixed in versions 1.107.6 and 2.44.0.","aliases":["GHSA-22h6-qm39-v87j"],"modified":"2026-10-10T02:47:38.980007654Z","published":"2026-10-08T15:18:40.047Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-1289","CWE-918"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/107xxx/CVE-2026-107288.json"},"references":[{"type":"WEB","url":"https://github.com/pydantic/pydantic-ai/releases/tag/v1.107.6"},{"type":"WEB","url":"https://github.com/pydantic/pydantic-ai/releases/tag/v2.44.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/107xxx/CVE-2026-107288.json"},{"type":"ADVISORY","url":"https://github.com/pydantic/pydantic-ai/security/advisories/GHSA-22h6-qm39-v87j"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-107288"},{"type":"FIX","url":"https://github.com/pydantic/pydantic-ai/commit/490335f8e2322e143a79337ddca9410e0176c812"},{"type":"FIX","url":"https://github.com/pydantic/pydantic-ai/commit/a9dab92099d0ef9d5d4aa34ccac8a6f1b0e51284"},{"type":"FIX","url":"https://github.com/pydantic/pydantic-ai/commit/c1f212a084cbfa0012f2044cdb4731d214b3b983"},{"type":"FIX","url":"https://github.com/pydantic/pydantic-ai/pull/8407"},{"type":"FIX","url":"https://github.com/pydantic/pydantic-ai/pull/8409"},{"type":"FIX","url":"https://github.com/pydantic/pydantic-ai/pull/8421"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/pydantic/pydantic-ai","events":[{"introduced":"a282bcade2c2a75847806bbba9cf511dd0623019"},{"introduced":"6001a4549018ad5509f2c11ed6c38d2385159506"},{"fixed":"7ee27e38ab2e525ca60ff1a25d16413ff989fd79"},{"fixed":"9fdabb4b2afb54ff7deb9013f6b43971324d9181"},{"fixed":"490335f8e2322e143a79337ddca9410e0176c812"},{"fixed":"a9dab92099d0ef9d5d4aa34ccac8a6f1b0e51284"},{"fixed":"c1f212a084cbfa0012f2044cdb4731d214b3b983"}],"database_specific":{"source":["AFFECTED_FIELD","REFERENCES"],"extracted_events":[{"introduced":"1.77.0"},{"fixed":"1.107.6"},{"introduced":"2.0.0b1"},{"fixed":"2.44.0"}]}}],"versions":["v1.107.5","v2.43.0","v2.42.0","v2.41.0","v2.40.0","v2.39.0","v2.38.0","v2.37.0","v2.36.0","v2.35.3","v2.35.1","v2.35.0","v2.34.0","v2.33.0","v2.32.2","v2.32.1","v2.32.0","v2.31.1","v2.31.0","v2.30.0","v1.107.4","v2.29.0","v2.28.0","v1.107.2","v2.27.1","v2.27.0","v1.107.1","v2.26.0","v2.25.0","v2.24.0","v2.23.0","v2.22.0","v2.21.0","v2.20.0","v2.19.0","v2.18.0","v2.17.0","v2.16.0","v2.15.0","v2.14.1","v2.14.0","v2.13.0","v2.12.0","v2.11.0","v2.10.0","v2.9.1","v2.9.0","v1.107.0","v2.8.0","v2.7.0","v2.6.0","v2.5.1","v2.5.0","v2.4.0","v2.3.0","v2.2.0","v2.1.0","v2.0.0","v1.106.0","v1.105.0","v1.104.0","v1.103.0","v1.102.0","v1.91.0","v1.101.0","v1.100.0","v1.99.0","v1.98.0","v1.97.0","v1.96.0","v1.96.1","v1.94.0","v1.95.1","v1.95.0","v1.93.0","v1.92.0","v1.90.0","v1.89.1","v1.89.0","v1.88.0","v1.87.0","v1.86.0","v1.86.1","v1.85.1","v1.85.0","v1.84.1","v1.84.0","v1.83.0","v1.82.0","v1.81.0","v1.80.0","v1.79.0","v1.78.0","v1.77.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-107288.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N"}]}