# CVE-2025-12739: Cross-Site Scripting (XSS) in Looker's Extension Loader leading to Admin Account Compromise

> An attacker with viewer permissions can execute scripts in an admin's browser via a malicious URL, leading to admin account compromise.

- **Severity:** High 7.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/U:Red`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 24 Nov 2025
- **Updated:** 24 Nov 2025
- **Also known as:** GHSA-mcm3-jr69-vvr3

## What is CVE-2025-12739?

CVE-2025-12739 is a high-severity cross-site scripting vulnerability in Google Cloud Looker, published on 24 Nov 2025. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

An attacker with viewer permissions in Looker could craft a malicious URL that, when opened by a Looker admin, would execute an attacker-supplied script. Exploitation required at least one Looker extension installed on the instance.

Looker-hosted and Self-hosted were found to be vulnerable.
This issue has already been mitigated for Looker-hosted instances. No user action is required for these.

Self-hosted instances must be upgraded as soon as possible. This vulnerability has been patched in all supported versions of Self-hosted.
The versions below have all been updated to protect from this vulnerability. You can download these versions at the Looker download page  https://download.looker.com/ :  *  24.18.201+
  *  25.0.79+
  *  25.6.66+
  *  25.12.7+
  *  25.16.0+
  *  25.18.0+
  *  25.20.0+

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2025-12739?


## How do I fix CVE-2025-12739?

No fix has been published for CVE-2025-12739 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-12739 being exploited?

There is no known exploitation of CVE-2025-12739 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-12739 and fix it if it is affected.

What it is: CVE-2025-12739 is a high-severity cross-site scripting vulnerability in Google Cloud Looker, published on 24 Nov 2025. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2025-12739 in the wild and no public exploit code.

Affected product: Google Cloud Looker. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-12739/ (Markdown: https://insights.sbomify.com/CVE-2025-12739/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-12739
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-12739
- OSV: https://osv.dev/vulnerability/CVE-2025-12739

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-12739/
Summaries are generated and may contain mistakes; the official description above is the record.