Vulnerability · Published Jun 16, 2026 · Assigned by GitHub_M
CVE-2026-48782pydantic-ai: SSRF blocklist bypass via IPv4-compatible, SIIT/IVI, and local NAT64 IPv6 addresses (incomplete fix of CVE-2026-46678)
Medium 6.8
In plain English
A medium-severity server-side request forgery in pydantic-ai from pydantic. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 35% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| PyPI | pydantic-ai | 1.102.0 | GHSA-cg7w-rg45-pc59 |
| PyPI | pydantic-ai | 2.0.0b3 | GHSA-cg7w-rg45-pc59 |
| PyPI | pydantic-ai | 1.102.0, 2.0.0b3 | PYSEC-2026-2977 |
| PyPI | pydantic-ai-slim | 1.102.0 | GHSA-cg7w-rg45-pc59 |
| PyPI | pydantic-ai-slim | 2.0.0b3 | GHSA-cg7w-rg45-pc59 |
| PyPI | pydantic-ai-slim | 1.102.0, 2.0.0b3 | PYSEC-2026-2981 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| pydantic | pydantic-ai | >= 1.56.0, < 1.102.0>= 2.0.0b1, < 2.0.0b3 |
| pydantic | pydantic-ai-slim | >= 2.0.0b1, < 2.0.0b3>= 1.56.0, < 1.102.0 |
Weakness: CWE-918 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:N
References
- https://github.com/pydantic/pydantic-ai/security/advisories/GHSA-cg7w-rg45-pc59 x_refsource_CONFIRM
- https://github.com/pydantic/pydantic-ai/pull/5596 x_refsource_MISC
- https://github.com/pydantic/pydantic-ai/commit/1add06179ba4de259f7ab977620b697b7209f7e4 x_refsource_MISC
- https://github.com/pydantic/pydantic-ai/releases/tag/v1.102.0 x_refsource_MISC