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Fencer Intel
high 7.5

CVE-2026-52844 json

Caddy: Windows `file_server` path authorization bypass via encoded backslash

published 4mo ago modified 17d ago also EUVD-2026-38557 , GHSA-qrp7-cvwr-j2c6 , GO-2026-5595

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 50%
public exploits
0
none known

Summary

Caddy is an extensible server platform that uses TLS by default. Prior to 2.11.4, on Windows, Caddy path matchers treat /private\secret.txt as outside /private/*, but file_server later resolves the same request path as private\secret.txt on disk. An unauthenticated remote client can bypass Caddy path-scoped auth/deny routes protecting /private/*. This vulnerability is fixed in 2.11.4.

Patch / fix

  • go github.com/caddyserver/caddy/v2 2.11.4
  • caddyserver caddy 2.11.4
  • govulncheck-vulndb SLES 16.0, SLES for SAP applications 16.0 0.0.20260727T201416-160000.1.1

suse advisories SUSE-SU-2026:23216-1SUSE-SU-2026:23227-1

  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260727T201416-160000.1.1

opensuse advisories openSUSE-SU-2026:21551-1

Is CVE-2026-52844 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
4mo ago

Exploit prediction

0.62% chance of exploitation in the next 30 days, higher than 50% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/caddyserver/caddy/security/advisories/GHSA-qrp7-cvwr-j2c6 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
go github.com/caddyserver/caddy/v2
<2.11.4
2.11.4
go github.com/caddyserver/caddy
<=1.0.5
 no fix listed

Affected products

  • caddyserver caddy

Classification

Weakness
  • CWE-22 Improper Limitation of a Pathname to a Restricted Directory
  • CWE-284 Improper Access Control

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.