{"id":"PYSEC-2026-2982","summary":"Pydantic AI: SSRF cloud-metadata blocklist bypass via IPv4-mapped IPv6 (Incomplete fix of CVE-2026-25580)","details":"## Summary\n\nWhen an application using Pydantic AI opts a URL into `force_download='allow-local'` (which disables the default block on private/internal IPs), the cloud-metadata blocklist could be bypassed by encoding the metadata IP in an IPv6 transition form (IPv4-mapped IPv6, 6to4, or NAT64). Dual-stack and translated networks route the IPv6 wrapper to the underlying IPv4 endpoint, exposing cloud IAM short-term credentials.\n\nThis is an incomplete fix of [GHSA-2jrp-274c-jhv3](https://github.com/pydantic/pydantic-ai/security/advisories/GHSA-2jrp-274c-jhv3) / [CVE-2026-25580](https://nvd.nist.gov/vuln/detail/CVE-2026-25580). The parent advisory's remediation guaranteed that \"cloud metadata endpoints are always blocked, even with `allow-local`.\" That guarantee did not hold for IPv6-encoded forms of the metadata IPs.\n\n## Severity\n\nSame impact metrics as the parent CVE, but materially narrower attack surface (AC:H instead of AC:L), because exploitation requires the application to have opted into `allow-local` on a URL influenced by untrusted input.\n\n## Who Is Affected\n\nApplications are affected **only if** they explicitly opt for `FileUrl` (`ImageUrl`, `AudioUrl`, `VideoUrl`, `DocumentUrl`) into `force_download='allow-local'` on a URL that is, or could be, influenced by untrusted input.\n\nApplications are **not** affected if they use any of the bundled integrations to ingest user input, because they do not propagate `force_download` from external data:\n\n- `Agent.to_web` / `clai web`\n- `VercelAIAdapter`\n- `AGUIAdapter` / `Agent.to_ag_ui`\n\nApplications that only download from developer-controlled URLs are not affected.\n\n## Remediation\n\nUpgrade to `1.99.0` or later. The cloud-metadata and private-IP blocklists now apply to IPv6 transition forms that route to a blocked IPv4 endpoint (IPv4-mapped IPv6, 6to4, and NAT64 well-known prefix). The blocklists have also been extended to cover additional IANA-reserved IPv4 and IPv6 special-purpose ranges.\n\n## Workaround for Unpatched Versions\n\nAvoid passing `force_download='allow-local'` on any URL that could be influenced by untrusted input. If developers must, resolve the hostname themselves and validate the result against their own metadata blocklist — including IPv6-encoded forms — before constructing the `FileUrl`.\n\n## Credits\n\nReported by [j0hndo](mailto:dohyun4466@gmail.com).","aliases":["CVE-2026-46678","GHSA-cqp8-fcvh-x7r3","PYSEC-2026-2978"],"modified":"2026-07-13T16:43:22.591175364Z","published":"2026-07-13T15:19:11.347900Z","references":[{"type":"WEB","url":"https://github.com/pydantic/pydantic-ai/security/advisories/GHSA-2jrp-274c-jhv3"},{"type":"WEB","url":"https://github.com/pydantic/pydantic-ai/security/advisories/GHSA-cqp8-fcvh-x7r3"},{"type":"PACKAGE","url":"https://github.com/pydantic/pydantic-ai"},{"type":"PACKAGE","url":"https://pypi.org/project/pydantic-ai-slim"},{"type":"ADVISORY","url":"https://github.com/advisories/GHSA-cqp8-fcvh-x7r3"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-46678"}],"affected":[{"package":{"name":"pydantic-ai-slim","ecosystem":"PyPI","purl":"pkg:pypi/pydantic-ai-slim"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.56.0"},{"fixed":"1.99.0"}]}],"versions":["1.56.0","1.57.0","1.58.0","1.59.0","1.60.0","1.61.0","1.62.0","1.63.0","1.64.0","1.65.0","1.66.0","1.67.0","1.68.0","1.69.0","1.70.0","1.71.0","1.72.0","1.73.0","1.74.0","1.75.0","1.76.0","1.77.0","1.78.0","1.79.0","1.80.0","1.81.0","1.82.0","1.83.0","1.84.0","1.84.1","1.85.0","1.85.1","1.86.0","1.86.1","1.87.0","1.88.0","1.89.0","1.89.1","1.90.0","1.91.0","1.92.0","1.93.0","1.94.0","1.95.0","1.95.1","1.96.0","1.96.1","1.97.0","1.98.0"],"database_specific":{"source":"https://github.com/pypa/advisory-database/blob/main/vulns/pydantic-ai-slim/PYSEC-2026-2982.yaml"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:N"}]}