CVE-2026-63439
2FAuth: Reverse Proxy Guard Trusts Client-Supplied Headers Without Proxy Verification
Description
2FAuth is a web app to manage Two-Factor Authentication (2FA) accounts and generate their security codes. Prior to 8.0.0, when AUTHENTICATION_GUARD=reverse-proxy-guard is enabled, ReverseProxyGuard::user() reads the default REMOTE_USER identity header, or a custom identity header selected by the AUTH_PROXY_HEADER_FOR_USER configuration setting, without confirming that the request originated from a configured trusted proxy. A remote client that can reach the application directly can forge the selected identity header and authenticate as an existing user, including an administrator, gaining access to stored 2FA secrets and account or application management functions. This issue is fixed in version 8.0.0.
INFO
Published Date :
Nov. 6, 2026, 8:22 p.m.
Last Modified :
Nov. 6, 2026, 8:22 p.m.
Remotely Exploit :
Yes !
Source :
GitHub_M
Affected Products
The following products are affected by CVE-2026-63439
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | CRITICAL | MITRE-CVE |
Solution
- Upgrade 2FAuth to version 8.0.0 or later.
- Ensure AUTHENTICATION_GUARD is configured correctly.
- Review and enforce trusted proxy configurations.
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CVE-2026-63439 vulnerability anywhere in the article.