# CVE-2026-46678: Pydantic AI: SSRF cloud-metadata blocklist bypass via IPv4-mapped IPv6 (Incomplete fix of CVE-2026-25580)

> Attackers can bypass cloud metadata blocklists via IPv6 encoding to steal IAM credentials if developers explicitly enable local file downloads.

- **Severity:** Medium 6.8 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 29 Jul 2026
- **Updated:** 30 Jul 2026
- **Also known as:** GHSA-cqp8-fcvh-x7r3, PYSEC-2026-2978, PYSEC-2026-2982, ROOT-APP-PYPI-CVE-2026-46678

## What is CVE-2026-46678?

CVE-2026-46678 is a medium-severity server-side request forgery vulnerability in pydantic-ai, published on 29 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Pydantic AI is a Python agent framework for building Generative AI applications. In versions 1.56.0 through 1.98.0, when an application opts a URL into force_download='allow-local' (disabling 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), exposing cloud IAM short-term credentials on dual-stack or translated networks. This is an incomplete fix of GHSA-2jrp-274c-jhv3 / CVE-2026-25580, whose remediation did not hold for IPv6-encoded forms of the metadata IPs. An application is affected only if it explicitly opts a FileUrl (ImageUrl, AudioUrl, VideoUrl, DocumentUrl) into force_download='allow-local' on a URL influenced by untrusted input; it is not affected when using bundled integrations to ingest user input (Agent.to_web / clai web, VercelAIAdapter, AGUIAdapter / Agent.to_ag_ui), since they do not propagate force_download from external data, nor when downloading only from developer-controlled URLs. This issue has been fixed in version 1.99.0.

Weakness: CWE-918 (Server-Side Request Forgery)

## Which versions are affected by CVE-2026-46678?

6 open source packages ship an affected version, including pydantic-ai and pydantic-ai-slim. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `pydantic-ai` | PyPI | From 1.56.0 | 1.99.0 |
| `pydantic-ai` | PyPI | From 1.56.0 | 1.99.0 |
| `pydantic-ai` | PyPI | From 1.56.0 | 1.99.0 |
| `pydantic-ai-slim` | PyPI | From 1.56.0 | 1.99.0 |
| `pydantic-ai-slim` | PyPI | From 1.56.0 | 1.99.0 |
| `pydantic-ai-slim` | PyPI | From 1.56.0 | 1.99.0 |

Products: Pydantic Pydantic Ai.

## How do I fix CVE-2026-46678?

Upgrade pydantic-ai to 1.99.0 or later.

## Is CVE-2026-46678 being exploited?

There is no known exploitation of CVE-2026-46678 in the wild and no public exploit code.

## Other vulnerabilities in pydantic-ai

- [CVE-2026-25580](https://insights.sbomify.com/CVE-2026-25580/): Pydantic AI Affected by Server-Side Request Forgery (SSRF) in URL Download Handling (high 8.6)
- [CVE-2026-107295](https://insights.sbomify.com/CVE-2026-107295/): Pydantic AI Web chat UI (`Agent.to_web()`, `clai web`): a website visited by the developer can trigger agent runs and server-side tool execution on the local chat endpoint (high 7.6)
- [CVE-2026-107286](https://insights.sbomify.com/CVE-2026-107286/): Pydantic AI: Concurrency-limited models can keep their slot when a streamed request ends early (high 7.5)
- [CVE-2026-25640](https://insights.sbomify.com/CVE-2026-25640/): Pydantic AI affected by Stored XSS via Path Traversal in Web UI CDN URL (high 7.1)
- [CVE-2026-107289](https://insights.sbomify.com/CVE-2026-107289/): Pydantic AI: SSRF cloud-metadata blocklist bypass via IPv6 zone identifiers (medium 6.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-46678 and fix it if it is affected.

What it is: CVE-2026-46678 is a medium-severity server-side request forgery vulnerability in pydantic-ai, published on 29 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-46678 in the wild and no public exploit code.

Affected packages and fixed versions:
- pydantic-ai (PyPI): affected from 1.56.0; fixed in 1.99.0
- pydantic-ai (PyPI): affected from 1.56.0; fixed in 1.99.0
- pydantic-ai (PyPI): affected from 1.56.0; fixed in 1.99.0
- pydantic-ai-slim (PyPI): affected from 1.56.0; fixed in 1.99.0
- pydantic-ai-slim (PyPI): affected from 1.56.0; fixed in 1.99.0
- pydantic-ai-slim (PyPI): affected from 1.56.0; fixed in 1.99.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-46678/ (Markdown: https://insights.sbomify.com/CVE-2026-46678/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46678
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46678
- OSV: https://osv.dev/vulnerability/CVE-2026-46678

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-46678/
Summaries are generated and may contain mistakes; the official description above is the record.