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CVE-2026-52845

8.1 · HIGH

Caddy is an extensible server platform that uses TLS by default.

Published Jun 23, 2026CWE-287EPSS 0.45%

Overview

CVE-2026-52845 is a high-severity vulnerability. It was published on June 23, 2026 and has a CVSS 3.1 base score of 8.1 (HIGH).

This vulnerability has a CVSS 3.1 base score of 8.1, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

Technical description

Caddy is an extensible server platform that uses TLS by default. Prior to 2.11.4, forward_auth copy_headers deletes the exact client-supplied identity header before copying the trusted value from the auth gateway. But when the request later goes through php_fastcgi, Caddy normalizes HTTP headers into CGI variables by replacing - with _. This lets a client send an underscore alias that survives the forward_auth delete step but becomes the same PHP/FastCGI variable. Result: a remote client can inject or sometimes override identity/group headers trusted by PHP/FastCGI applications behind Caddy. This vulnerability is fixed in 2.11.4.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/caddyserver/caddy/security/advisories/GHSA-f59h-q822-g45gRefaccess.redhat.com/security/cve/CVE-2026-52845Refbugzilla.redhat.com/show_bug.cgi?id=2491907GitHubgithub.com/caddyserver/caddy/security/advisories/GHSA-f59h-q822-g45gRefsecurity.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-52845.json

How CyberStrike helps

Frequently asked questions

What is CVE-2026-52845?

CVE-2026-52845 is a high-severity vulnerability. It was published on June 23, 2026 and has a CVSS 3.1 base score of 8.1 (HIGH).

How severe is CVE-2026-52845?

This vulnerability has a CVSS 3.1 base score of 8.1, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-52845?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-52845?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-52845 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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