pydantic-ai: SSRF blocklist bypass via IPv4-compatible, SIIT/IVI, and local NAT64 IPv6 addresses (incomplete fix of CVE-2026-46678)_CVE-2026-48782

{
    "lastseen": "",
    "description": "Pydantic AI is a Python agent framework for building applications and workflows with Generative AI. In versions 1.56.0 through 1.101.0, 2.0.0b1, and 2.0.0b2, the cloud-metadata blocklist could be bypassed by encoding the metadata IP in an IPv6 transition form that the previous fix, CVE-2026-46678, did not decode, exposing cloud IAM short-term credentials. The previous remediation decoded only IPv4-mapped IPv6, 6to4, and the NAT64 well-known prefix, so the metadata guarantee did not hold for the remaining transition forms: IPv4-compatible IPv6 (::a.b.c.d), the NAT64 RFC 8215 local-use prefix (64:ff9b:1::/48), operator-chosen NAT64 prefixes, and ISATAP. The IPv6 wrapper is then delivered to the underlying IPv4 metadata endpoint. This occurs when an application using Pydantic AI opts a URL into force_download='allow-local' (which disables the default block on private/internal IPs) and runs on a network that actually routes the affected IPv6 transition forms: NAT64-configured networks (IPv6-only or dual-stack-with-NAT64 deployments, including some Kubernetes setups) for the NAT64 variants, or networks with an ISATAP tunnel for ISATAP. A standard dual-stack cloud VM or container does not route these forms and is not affected in practice. The IPv4-compatible and Teredo variants are deprecated and addressed as defense-in-depth. This is an incomplete fix of GHSA-cqp8-fcvh-x7r3 / CVE-2026-46678 (itself a follow-up to CVE-2026-25580). This issue has been fixed in version 2.0.0b3.",
    "published": "2026-06-16T22:49:26.750Z",
    "modified": "2026-06-16T22:49:26.750Z",
    "type": "cve",
    "title": "pydantic-ai: SSRF blocklist bypass via IPv4-compatible, SIIT/IVI, and local NAT64 IPv6 addresses (incomplete fix of CVE-2026-46678)",
    "source": "GitHub_M",
    "references": "https://github.com/pydantic/pydantic-ai/security/advisories/GHSA-cg7w-rg45-pc59\nhttps://github.com/pydantic/pydantic-ai/pull/5596\nhttps://github.com/pydantic/pydantic-ai/commit/1add06179ba4de259f7ab977620b697b7209f7e4\nhttps://github.com/pydantic/pydantic-ai/releases/tag/v1.102.0",
    "id": "CVE-2026-48782",
    "bulletinFamily": "",
    "cwe": [
        "CWE-918"
    ],
    "cvelist": null,
    "sourceData": "pydantic pydantic-ai >= 1.56.0, < 1.102.0\npydantic pydantic-ai >= 2.0.0b1, < 2.0.0b3\npydantic pydantic-ai-slim >= 2.0.0b1, < 2.0.0b3\npydantic pydantic-ai-slim >= 1.56.0, < 1.102.0",
    "sourceHref": "",
    "cvss": {
        "score": 6.8,
        "severity": "MEDIUM",
        "vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:N",
        "version": "3.1"
    },
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        "baseScore": 0,
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        "cvssV3": {
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    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "pydantic-ai",
    "version": ">= 1.56.0, < 1.102.0",
    "vendor": "pydantic",
    "ai_description": "",
    "ai_severity": "",
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    "ai_score": 0
}