Path Traversal in pydantic-ai (CVE-2026-25640)
Summary
Path traversal in pydantic-ai (CVE-2026-25640). Confidential information can be exposed externally. Mitigation: upgrade to 1.51.0 or later.
Original description
The description as published by the source.
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.
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-25640 has been found in pydantic-ai.
Confidential information can be exposed externally. CVSS score: 7.1/10.
What to do: upgrade pydantic-ai to 1.51.0 or later.
If unsure, ask your IT team or search "pydantic-ai CVE-2026-25640" on the vendor's site.
CVE-2026-25640 (pydantic-ai) — CWE-22 / CVSS v3 7.1
Attack vector: remote (network-reachable) / unauthenticated
Patched: 1.51.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Path traversal (CWE-22) exists in pydantic-ai.
Check the vendor advisory for the affected versions of pydantic-ai.
Severity: High (CVSS 7.1/10). Confidential information can be exposed externally.
Update to 1.51.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'pydantic-ai' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'pydantic-ai' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
pydantic-aiを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade pydantic-ai to 1.51.0ステージング環境で 1.51.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory github.com
- advisory access.redhat.com
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- report bugzilla.redhat.com
- web github.com
- web security.access.redhat.com