# CVE-2026-73374: Stored Cross-Site Scripting (XSS) via Unescaped CNA Reference Tags in vulnerability-lookup

> Authenticated users can inject malicious scripts via reference tags, leading to JavaScript execution in other users' browsers.

- **Severity:** Medium 6.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:H/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 12 Aug 2026
- **Updated:** 12 Aug 2026
- **Also known as:** GHSA-xx2h-7258-xw7c

## What is CVE-2026-73374?

CVE-2026-73374 is a medium-severity cross-site scripting vulnerability in vulnerability-lookup, published on 12 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

A stored cross-site scripting (XSS) vulnerability existed in Vulnerability-Lookup in the render_tag_badges Jinja filter used to display reference tags associated with vulnerability records.

Values from containers.cna.references[].tags[] were directly interpolated into HTML badge elements and the resulting string was wrapped in markupsafe.Markup. Because Markup marks the generated content as safe, Jinja's automatic HTML escaping was bypassed.

An authenticated user with permissions to create or modify vulnerability records, such as a user holding the vulnerability:create or vulnerability:modify permission, could submit a crafted reference tag through the CNA API containing arbitrary HTML or JavaScript-capable markup.

The malicious value would subsequently be stored as part of the vulnerability record. When another user visited the corresponding public /cve/<id> or /vuln/<id> page, the crafted tag would be rendered as HTML in the viewer's browser. This could result in JavaScript execution in the security context of the Vulnerability-Lookup application.

Successful exploitation could allow an attacker to perform actions in the context of a victim, access information available to the victim's browser session, or modify page content. As the affected vulnerability pages can be accessed publicly, exploitation may affect users who are not authenticated.

The issue was corrected by applying markupsafe.escape() to each reference tag before inserting it into the HTML badge markup, while retaining Markup only for the static HTML scaffolding.

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

## Which versions are affected by CVE-2026-73374?


## How do I fix CVE-2026-73374?

No fix has been published for CVE-2026-73374 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-73374 being exploited?

There is no known exploitation of CVE-2026-73374 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-73374 and fix it if it is affected.

What it is: CVE-2026-73374 is a medium-severity cross-site scripting vulnerability in vulnerability-lookup, published on 12 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-73374 in the wild and no public exploit code.

Affected product: vulnerability-lookup. 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-2026-73374/ (Markdown: https://insights.sbomify.com/CVE-2026-73374/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-73374
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-73374
- OSV: https://osv.dev/vulnerability/CVE-2026-73374

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-73374/
Summaries are generated and may contain mistakes; the official description above is the record.