# CVE-2026-63442: OPNsense: Log Forgery via Login Username CRLF in WebGUI Authentication → Pf Table IP Blocking

> Unauthenticated attackers can inject CRLF characters into the login username to forge syslog entries, blocking legitimate IPs or bypassing lockout mechanisms.

- **Severity:** High 8.1 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 15 Oct 2026
- **Updated:** 16 Oct 2026
- **Also known as:** GHSA-2v2x-m4j7-76pv

## What is CVE-2026-63442?

CVE-2026-63442 is a high-severity vulnerability in opnsense core, published on 15 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

OPNsense is a FreeBSD based firewall and routing platform. Prior to version 26.1.11, the unauthenticated WebGUI login usernamefld accepts carriage-return and line-feed characters that survive LOG_AUTH processing through syslog-ng-lockout.conf into the syslog-ng program destination feeding lockout_handler. The consumer's readline() processing treats an injected fragment as a separate authentication event and selects the first syntactically valid IP address from the forged line. An attacker with network access to the login page can forge failure events for another IP, causing that IP to be added to the sshlockout PF table and its active states to be killed, or forge accepted events that reset an attacker's own brute-force counter. This can block administrative, DNS, gateway, or monitoring addresses and can bypass password-guessing lockout without authentication. This issue is fixed in version 26.1.11.

Weakness: CWE-117 (Improper Output Neutralization for Logs)

## Which versions are affected by CVE-2026-63442?


## How do I fix CVE-2026-63442?

No fix has been published for CVE-2026-63442 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-63442 being exploited?

There is no known exploitation of CVE-2026-63442 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-63442 and fix it if it is affected.

What it is: CVE-2026-63442 is a high-severity vulnerability in opnsense core, published on 15 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-63442 in the wild and no public exploit code.

Affected product: opnsense core. 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-2026-63442/ (Markdown: https://insights.sbomify.com/CVE-2026-63442/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63442
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63442
- OSV: https://osv.dev/vulnerability/CVE-2026-63442

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-63442/
Summaries are generated and may contain mistakes; the official description above is the record.