CVE-2026-10032: @a2ui/web_core: `openUrl` permits `javascript:` URI execution via agent-supplied button actions

Should you act?

Normal patch cycle

No exploitation signal; fix it in your next routine update if you are affected. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 0.1%, percentile 2: FIRST’s model estimates a 0.1% chance of exploitation activity in the next 30 days, higher than 2% of all scored CVEs (low). EPSS is a probability, not a verdict.
• Needs an account (low (any account)). Exposure depends on who can log in.
• Only applies if your dependency tree includes @a2ui/web_core (npm) >= 0.9.0, < 0.10.2, fixed in 0.10.2. Check your lockfile, including transitive dependencies.

What it is

The openUrl function in @a2ui/webcore passes an agent-controlled URL directly to window.open() without validating the URI scheme. A malicious agent can supply a javascript: URI as the url argument of a Button component's functionCall action. When the user clicks the rendered button, arbitrary JavaScript executes in the victim application's browser origin, constituting a stored/reflected XSS with Critical severity. No non-default configuration is required; the Basic Catalog is enabled by default.

From the GitHub advisory

Summary

The openUrl function in @a2ui/webcore passes an agent-controlled URL directly to window.open() without validating the URI scheme. A malicious agent can supply a javascript: URI as the url argument of a Button component's functionCall action. When the user clicks the rendered button, arbitrary JavaScript executes in the victim application's browser origin, constituting a stored/reflected XSS. No non-default configuration is required; the Basic Catalog is enabled by default.

Details

The vulnerability exists in the openUrl function implementation within the Basic Catalog of @a2ui/webcore (commit 23a003248abbf59da6c376ea64ace91d82d209ff).

Sink — renderers/webcore/src/v09/basiccatalog/functions/basicfunctions.ts:428-430:

Weakness type: CWE-79.

Product: @a2ui/web_core (npm) · Assigned by: Google · Published: 2026-08-04

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: none
• Privileges required: low (any account)
• User interaction: passive

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.12% probability of exploitation activity in the next 30 days; percentile 2.

Timeline

• 2026-08-04 — CVE record last updated
• 2026-08-04 — CVE record published by Google
• 2026-10-02 — GitHub-reviewed advisory GHSA-72qq-p3r5-f7wq published (critical)

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-72qq-p3r5-f7wq github.com
2. CVE.org record CVE-2026-10032 cve.org
3. NVD entry CVE-2026-10032 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com

Critical npm advisories · Today’s Security Digest