Pydantic AI Web chat UI (`Agent.to_web()`, `clai web`): the local chat endpoint does not validate the `Host` header (pydantic pydantic-ai)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.13 % · percentile 3 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- GitHub_M
- NVD status
- Analyzed
Description
Pydantic AI is a Python agent framework for building applications and workflows with Generative AI. From 1.34.0 until 2.30.0, the Agent.to_web() and clai web development chat server does not validate the Host header, allowing a website visited by a developer to use DNS rebinding to reach a loopback-hosted agent as a same-origin service. The hostile page can read the served UI and submit chat requests that execute agent tools with the local process's privileges and credentials, causing data disclosure or unwanted side effects. Binding to localhost, Origin checks, and CSRF tokens do not prevent the same-origin DNS rebinding path. This issue is fixed in versions 1.107.5 and 2.30.0.
Weaknesses (CWE)
- CWE-346 — Origin Validation Error
- CWE-350 — Reliance on Reverse DNS Resolution for a Security-Critical Action
References
- https://github.com/pydantic/pydantic-ai/security/advisories/GHSA-q2xc-rrxj-58x9
- https://github.com/pydantic/pydantic-ai/pull/7437
- https://github.com/pydantic/pydantic-ai/pull/7438
- https://github.com/pydantic/pydantic-ai/commit/394cc1d31656620704a703a2daed752afa5135fe
- https://github.com/pydantic/pydantic-ai/commit/871c7aeec5dfed2138655ccbccbf15c6d763bae7
- https://github.com/pydantic/pydantic-ai/releases/tag/v1.107.5
- https://github.com/pydantic/pydantic-ai/releases/tag/v2.30.0
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | MEDIUM 6.4 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:L | GitHub_M |
| CVSS 3.1 | MEDIUM 6.4 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:L | NVD · security-advisories@github.com (Secondary) |
Advisories
- GHSA-q2xc-rrxj-58x9 — Pydantic AI Web chat UI (`Agent.to_web()`, `clai web`): the local chat endpoint does not validate the `Host` header
- PYSEC-2026-4279 — Pydantic AI Web chat UI (`Agent.to_web()`, `clai web`): the local chat endpoint does not validate the `Host` header
- PYSEC-2026-4288 — Pydantic AI Web chat UI (`Agent.to_web()`, `clai web`): the local chat endpoint does not validate the `Host` header
European references
- ENISA EUVD · EUVD-2026-95099
- GCVE · GCVE-0-2026-107292
CERT-FR advisories
- CERTFR-2026-AVI-1385 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
Affected configurations (NVD CPE)
cpe:2.3:a:pydantic:pydantic_ai:*:*:*:*:*:python:*:*≥ 1.34.0 < 1.107.5cpe:2.3:a:pydantic:pydantic_ai:*:-:*:*:*:python:*:*≥ 2.0.0 < 2.30.0
Affected products
| Product | Versions |
|---|---|
| pydantic · pydantic-ai | affected >= 1.34.0, < 2.0.0b1 ; affected >= 2.0.0b1, < 2.30.0 |
| pydantic · pydantic-ai-slim | affected >= 1.34.0, < 2.0.0b1 ; affected >= 2.0.0b1, < 2.30.0 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| CERT-FR (ANSSI) | Licence Ouverte / Etalab 2.0 |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |