# CVE-2026-118537: a2ui improper input validation in media components URL

Source: https://junglewise.ai/threats/cve-2026-118537-a-vulnerability-was-found-in-a2ui-up-to-0-10-4-this  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-28. Updated: 2026-10-28  
License: CC BY 4.0 with a link back

CVE-2026-118537 · Severity: medium · CVSS 4.3 · Published 2026-10-28

a2ui is a web UI component library used to render dynamic user interfaces. The Image, Video, and Audio Player components accept a URL parameter from an untrusted source and directly bind it to the media element's src attribute without validating the URL scheme. This allows an attacker to inject data:, javascript:, file:, or blob: URLs, causing the victim's browser to make credential-bearing requests to internal endpoints, enabling credential theft, internal network probing, and UI-based attacks.

Technologies: [A2ui-Project A2ui](https://junglewise.ai/threats/technologies/a2ui-project-a2ui). Vendors: [A2ui-Project](https://junglewise.ai/threats/vendors/a2ui-project).

## Quick answers

**Is CVE-2026-118537 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-118537 being exploited in the wild.

**How severe is CVE-2026-118537?** Medium severity, with a CVSS score of 4.3, published 28 October 2026.

**Which products and versions are affected?** A2ui-Project A2ui up to 0.10.4; A2ui-Project Lit up to 0.10.4; A2ui-Project Web Core 0.11.0, 0.12.0.

**Is there a fix for CVE-2026-118537?** No fixed version is recorded yet. Validate the URL scheme to allow only http: and https: before binding to the src attribute of media elements, mirroring the fix applied to the openUrl action in CVE-2026-10032.</anigation>
<parameter name="timeline">[{"kind":"disclosed","at":"2026-10-08","note":"Issue #3077 opened"},{"kind":"advisory","at":"2026-10-28","note":"CVE-2026-118537 published"}] If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-118537 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-118537?** Check whether you run A2ui-Project A2ui, A2ui-Project Lit or A2ui-Project Web Core at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix


Validate the URL scheme to allow only http: and https: before binding to the src attribute of media elements, mirroring the fix applied to the openUrl action in CVE-2026-10032.</anigation>
<parameter name="timeline">[{"kind":"disclosed","at":"2026-10-08","note":"Issue #3077 opened"},{"kind":"advisory","at":"2026-10-28","note":"CVE-2026-118537 published"}]

## Technical details

The vulnerability is improper input validation (CWE-20) in the Image, Video, and AudioPlayer components across @a2ui/web_core and @a2ui/lit packages. The agent-supplied url property is rendered directly into the src attribute without scheme validation, allowing non-http(s) URLs including data:, javascript:, and file: schemes. An attacker can inject arbitrary URLs to trigger credential-bearing blind requests, internal endpoint probing, or content spoofing; a fix is available as PR #3108 which adds scheme validation.

## Affected products

- a2ui-project a2ui up to 0.10.4
- a2ui-project web_core 0.11.0, 0.12.0
- a2ui-project lit up to 0.10.4

## References

- [https://github.com/a2ui-project/a2ui/issues/3077](https://github.com/a2ui-project/a2ui/issues/3077)
- [https://github.com/a2ui-project/a2ui/pull/3108](https://github.com/a2ui-project/a2ui/pull/3108)

## Related threats

- [a2ui legacy Lit renderer uncontrolled property injection](https://junglewise.ai/threats/cve-2026-118538-a-vulnerability-was-determined-in-a2ui-project-a2ui-up-to-0-12-0)
- [a2ui uncontrolled recursion in DynamicValue resolver](https://junglewise.ai/threats/cve-2026-118275-a-vulnerability-was-found-in-a2ui-project-a2ui-up-to-0-10-6-this)
- [a2ui generic-binder resource consumption via unbounded child list](https://junglewise.ai/threats/cve-2026-118274-a-vulnerability-has-been-found-in-a2ui-project-a2ui-up-to-0-10-6)
- [a2ui DataModel.set resource consumption via unbounded array indices](https://junglewise.ai/threats/cve-2026-118273-a-flaw-has-been-found-in-a2ui-project-a2ui-up-to-0-10-6-affected)
- [a2ui information exposure through error messages](https://junglewise.ai/threats/cve-2026-118272-a-vulnerability-was-detected-in-a2ui-project-a2ui-up-to-0-10-6)