CVE-2026-4995Public exploitNetwork attack vector

Browser code execution via unsanitized annotator messages

Published Mar 28, 2026 · Updated Mar 28, 2026

Cross-site scripting in the OpenUI 1.0 annotator allows context-dependent attackers to execute JavaScript through generated UI content. The window message handler assigns event.data.html to wrapper.innerHTML and appends event.data.js as script elements without sanitization or origin validation. Exploitation requires a user-configured malicious or compromised LLM endpoint and a submitted prompt; injected code can read same-origin cookies and browser storage.

CVSS severity3.5
Low
EPSS probability0.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Cross-site scripting in the OpenUI 1.0 annotator allows context-dependent attackers to execute JavaScript through generated UI content. The window message handler assigns event.data.html to wrapper.innerHTML and appends event.data.js as script elements without sanitization or origin validation. Exploitation requires a user-configured malicious or compromised LLM endpoint and a submitted prompt; injected code can read same-origin cookies and browser storage.

The record

CVE
CVE-2026-4995
Published
Mar 28, 2026
Updated
Mar 28, 2026
Vendor
Weights & Biases
Product
OpenUI
Classifications
CWE-94, CWE-79, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 28, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 28, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=1.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Weights & Biases · OpenUIversion=1.0

Published CVSS scores

2.0VulDBCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P
3.5VulDBCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N
4.0VulDBAV:N/AC:L/Au:S/C:N/I:P/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-94Improper Control of Generation of Code ('Code Injection')
CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

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

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo