CVE-2026-52844: Caddy path authorization bypass on Windows via encoded backslash

CVE-2026-52844 · Severity: high · CVSS 7.5 · Published 2026-06-23

Caddy is a popular web server used to host websites and manage internet traffic. On Windows systems, a flaw in how the server handles file paths allows unauthorized users to bypass security rules intended to protect private folders. This could allow an attacker to view sensitive files, such as backups or credentials, that were supposed to be restricted by a password or access control list.

Technologies: Caddyserver Caddy, github.com/caddyserver/caddy (Go), github.com/caddyserver/caddy/v2 (Go). Vendors: Caddyserver, Go.

Quick answers

Is CVE-2026-52844 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-52844 being exploited in the wild.
How severe is CVE-2026-52844?
High severity, with a CVSS score of 7.5, published 23 June 2026.
Which products and versions are affected?
Caddyserver Caddy v2 < 2.11.4, <= 1.0.5; github.com/caddyserver/caddy (Go) <= 1.0.5, SEMVER:introduced=0,last_affected=1.0.5; github.com/caddyserver/caddy/v2 (Go) < 2.11.4, SEMVER:introduced=0,fixed=2.11.4.
Is there a fix for CVE-2026-52844?
Yes. github.com/caddyserver/caddy/v2 (Go): upgrade to 2.11.4 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-52844 attacked?
It is attacked over the network, in a web application.
Am I affected by CVE-2026-52844?
Check whether you run Caddyserver Caddy, github.com/caddyserver/caddy (Go) or github.com/caddyserver/caddy/v2 (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • github.com/caddyserver/caddy/v2 (Go): upgrade to 2.11.4 or later
    go get github.com/caddyserver/caddy/v2@v2.11.4

Technical details

A path normalization discrepancy exists in Caddy's Windows implementation between the request matcher and the file server component. Caddy's 'MatchPath.MatchWithError()' function treats backslashes (e.g., /private\secret.txt) as literal characters rather than directory separators, causing it to skip security rules defined for '/private/*'. However, the 'file_server' module later resolves these backslashes as valid separators on the Windows filesystem. An unauthenticated remote attacker can exploit this by using encoded backslashes (%5c) in a URL to bypass 'basic_auth' or 'respond 403' directives and read sensitive files. This issue is fixed in version 2.11.4.

Affected products

  • Caddyserver Caddy < 2.11.4

Identifiers

  • CVE-2026-52844
  • GHSA-qrp7-cvwr-j2c6
  • GO-2026-5595

Timeline

  • 2026-06-08: advisory: GitHub Security Advisory published
  • 2026-06-23: disclosed: NVD publication date
  • 2026-06-23: patched: Fix released in version 2.11.4

References

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