# CVE-2026-49131: OPNsense < 26.1.9 Stored XSS via Firewall Rule Description Field

> Authenticated attackers can inject scripts into firewall rule descriptions, leading to session hijacking or credential theft for other users.

- **Severity:** Medium 5.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/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:** 3 Aug 2026
- **Updated:** 14 Aug 2026
- **Also known as:** GHSA-2wfc-8j3p-p6cp

## What is CVE-2026-49131?

CVE-2026-49131 is a medium-severity cross-site scripting vulnerability in Deciso B.V. OPNsense, published on 3 Aug 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

OPNsense before 26.1.9 contains a stored cross-site scripting vulnerability that allows authenticated attackers with firewall rule management privileges to inject arbitrary HTML or JavaScript by embedding payloads in the firewall rule description field via the filter API endpoint. The unsanitized description value is persisted and later rendered through the default cell formatter in opnsense_bootgrid.js, which assigns raw cell content to innerHTML, causing injected scripts to execute in the browser of any authenticated user who views the Firewall Rules page, enabling session hijacking or credential theft.

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

## Which versions are affected by CVE-2026-49131?


## How do I fix CVE-2026-49131?

No fix has been published for CVE-2026-49131 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-49131 being exploited?

There is no known exploitation of CVE-2026-49131 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-49131 and fix it if it is affected.

What it is: CVE-2026-49131 is a medium-severity cross-site scripting vulnerability in Deciso B.V. OPNsense, published on 3 Aug 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-2026-49131 in the wild and no public exploit code.

Affected product: Deciso B.V. OPNsense. 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-2026-49131/ (Markdown: https://insights.sbomify.com/CVE-2026-49131/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-49131
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-49131
- OSV: https://osv.dev/vulnerability/CVE-2026-49131

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-49131/
Summaries are generated and may contain mistakes; the official description above is the record.