CVE-2026-25640Pydantic AI is a Python agent framework for building applications and workflows with Generative AI.
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Pydantic AI is a Python agent framework for building applications and workflows with Generative AI. From 1.34.0 to before 1.51.0, a path traversal vulnerability in the Pydantic AI web UI allows an attacker to serve arbitrary JavaScript in the context of the application by crafting a malicious URL. In affected versions, the CDN URL is constructed using a version query parameter from the request URL. This parameter is not validated, allowing path traversal sequences that cause the server to fetch and serve attacker-controlled HTML/JavaScript from an arbitrary source on the same CDN, instead of the legitimate chat UI package. If a victim clicks the link or visits it via an iframe, attacker-controlled code executes in their browser, enabling theft of chat history and other client-side data. This vulnerability only affects applications that use Agent.to_web to serve a chat interface and clai web to serve a chat interface from the CLI. These are typically run locally (on localhost), but may also be deployed on a remote server. This vulnerability is fixed in 1.51.0.
- CVSS
- 5.4 MEDIUM (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
- Weakness (CWE)
- CWE-22, CWE-79
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Not given
- NVD analysis
- Modified
- Record last updated
- Jul 15, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
pydantic pydantic_ai pydantic:pydantic_ai | from 1.34.0 before 1.51.0 | NVD |
References
- https://github.com/pydantic/pydantic-ai/releases/tag/v1.51.0product, release-notes
- https://github.com/pydantic/pydantic-ai/security/advisories/GHSA-wjp5-868j-wqv7vendor-advisory
- https://access.redhat.com/security/cve/CVE-2026-25640
- https://bugzilla.redhat.com/show_bug.cgi?id=2437753
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-25640.json
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.