# CVE-2026-27639: Mercator vulnerable to stored XSS via unescaped Blade directives in display templates

> Authenticated users can inject JavaScript via unescaped Blade directives, leading to code execution in other users' browsers.

- **Severity:** High 8.5 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N`)
- **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:** 25 Feb 2026
- **Updated:** 25 Feb 2026
- **Also known as:** GHSA-65p7-pph2-966g

## What is CVE-2026-27639?

CVE-2026-27639 is a high-severity cross-site scripting vulnerability in dbarzin mercator, published on 25 Feb 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

Mercator is an open source web application designed to enable mapping of information systems. A stored Cross-Site Scripting (XSS) vulnerability exists in Mercator prior to version 2026.02.22 due to the use of unescaped Blade directives (`{!! !!}`) in display templates. An authenticated user with the User role can inject arbitrary JavaScript payloads into fields such as "contact point" when creating or editing entities. The payload is then executed in the browser of any user who views the affected page, including administrators. Version 2026.02.22 fixes the vulnerability.

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

## Which versions are affected by CVE-2026-27639?

It affects 1 product.


Products: Sourcentis Mercator.

## How do I fix CVE-2026-27639?

No fix has been published for CVE-2026-27639 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-27639 being exploited?

There is no known exploitation of CVE-2026-27639 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-27639 and fix it if it is affected.

What it is: CVE-2026-27639 is a high-severity cross-site scripting vulnerability in dbarzin mercator, published on 25 Feb 2026. 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-2026-27639 in the wild and no public exploit code.

Affected product: dbarzin mercator. 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-2026-27639/ (Markdown: https://insights.sbomify.com/CVE-2026-27639/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-27639
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-27639
- OSV: https://osv.dev/vulnerability/CVE-2026-27639

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-27639/
Summaries are generated and may contain mistakes; the official description above is the record.