CVE-2026-25640Network attack vector

Browser script execution via traversed CDN URL

Published Feb 6, 2026 · Updated Feb 6, 2026

Path traversal in the Pydantic AI web UI allows remote attackers to run JavaScript in a victim's browser via a crafted URL. The web UI inserts the request's unvalidated version parameter into a CDN URL, so traversal sequences select attacker-controlled HTML from the same CDN. Exploitation requires an Agent.to_web or clai web chat interface and a victim to open the link or iframe; the script can read chat history and non-HttpOnly cookies.

CVSS severity7.1
High
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in the Pydantic AI web UI allows remote attackers to run JavaScript in a victim's browser via a crafted URL. The web UI inserts the request's unvalidated version parameter into a CDN URL, so traversal sequences select attacker-controlled HTML from the same CDN. Exploitation requires an Agent.to_web or clai web chat interface and a victim to open the link or iframe; the script can read chat history and non-HttpOnly cookies.

The record

CVE
CVE-2026-25640
Published
Feb 6, 2026
Updated
Feb 6, 2026
Vendor
Pydantic
Product
Pydantic AI
Classifications
CWE-79, CWE-22, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 6, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 6, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 1.34.0, < 1.51.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Pydantic · Pydantic AIversion=>= 1.34.0, < 1.51.0

Published CVSS scores

7.1redhat-SADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N
5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
7.1GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
T1189Drive-by Compromise

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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