🛡️ CVE-2026-52845 on Debian — caddy

⚪ Unknown ✅ No Known Exploit OSV
N/A
CVSS Score
0 Low4 Medium7 High9 Critical10

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.

Distribution advisory

This page covers CVE-2026-52845 as tracked by Debian, for the package caddy. The fix is available in version 2.11.4-1; earlier versions remain affected.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability none.

Weakness class

DEBIAN-CVE-2026-52845 is classified as CWE-287: Improper Authentication. The identity of the caller is not established correctly, so an attacker can act as another user.

Affected software

DEBIAN-CVE-2026-52845 is recorded against 1 package.

  • caddy (fixed in 2.11.4-1)

Timeline and source

Published on 23 June 2026 and last revised on 11 August 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

security-tracker.debian.org (Advisory)

Details

Severity Unknown
CVSS Score N/A
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2026-06-23
Updated 2026-08-12
Modified 2026-08-11
Fix URL N/A

Affected Packages

Software From version Fixed in
caddy 2.11.4-1

Similar Threats

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DEBIAN-CVE-2026-52845 is rated CVSS 8.1 High. BotEraser scans your installation against known CVE records and tells you whether this vulnerability applies to the versions you actually run.

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