CVE-2026-107292: Pydantic AI Web chat UI (`Agent.to_web()`, `clai web`): the local chat endpoint does not validate the `Host` header
Vulnerability summary
CVE-2026-107292 is a medium (CVSS 6.4) Origin Validation Error vulnerability in pydantic pydantic_ai. EPSS estimates a 0.13% chance of exploitation in the next 30 days, higher than 2.8% of scored vulnerabilities.
Not severe (CVSS 6.4, network access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Timeline
- 08-10-2026PublishedVulnerability first disclosed.
- 14-10-2026Last modifiedVulnerability information updated.
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.
CVSS metrics
3 scores · 3 sources · 1 version- OSV · PypiEcosystem advisory · calculated6.4MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:L
- NVDNIST6.4MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:L
EPSS trend
Probability
0.13%
Chance of exploitation in the next 30 days
Percentile
3%
Versus all other CVEs
30-day change
Change unavailable
Change unavailable
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-346Origin Validation ErrorThe product does not properly verify that the source of data or communication is valid.
- CWE-350Reliance on Reverse DNS Resolution for a Security-Critical ActionThe product performs reverse DNS resolution on an IP address to obtain the hostname and make a security decision, but it does not properly ensure that the IP address is truly associated with the hostname.
Affected systems
Known conditions: network-reachable, no authentication, user interaction (CVSS vector). Other conditions: not stated in public data.
Pydantic3 products
- pydantic_ai≥ 1.34.0, < 1.107.5 | ≥ 2.0.0, < 2.30.0
- pydantic-ai≥ 1.34.0, < 2.0.0b1 | ≥ 2.0.0b1, < 2.30.0
- pydantic-ai-slim≥ 1.34.0, < 2.0.0b1 | ≥ 2.0.0b1, < 2.30.0
PyPI2 products
- pydantic-ai≥ 1.34.0, < 1.107.5 | ≥ 2.0.0b1, < 2.30.0
- pydantic-ai-slim≥ 1.34.0, < 1.107.5 | ≥ 2.0.0b1, < 2.30.0
2 vendors · 5 products
References
12 links- github.com/pydantic/pydantic-ai/security/advisories/GHSA-q2xc-rrxj-58x9X Refsource CONFIRMWEBVendor Advisory
- github.com/pydantic/pydantic-ai/commit/394cc1d31656620704a703a2daed752afa5135feX Refsource MISCWEBPatch
- github.com/pydantic/pydantic-ai/commit/871c7aeec5dfed2138655ccbccbf15c6d763bae7X Refsource MISCWEBPatch
- github.com/pydantic/pydantic-ai/releases/tag/v1.107.5X Refsource MISCWEBPatchRelease NotesVendor Advisory
- github.com/pydantic/pydantic-ai/releases/tag/v2.30.0X Refsource MISCWEBPatchRelease NotesVendor Advisory
- pypi.org/project/pydantic-aiPACKAGE
