CVE-2026-52844 | Caddy: Windows `file_server` path authorization bypass via encoded backslash

Exp

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.

Published: 2026-06-23 Last update: 2026-06-29 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-52844 is rated Exploit Available (56.3/100): CVSS High severity, with low exploitation likelihood (EPSS 0.40%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2026-52844

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2026-52844

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-24 0.03% 0.40% +0.37%
2 2026-06-12 — 0.03% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-52844

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2026-52844

GitHub Security Advisory for CVE-2026-52844

GHSA-qrp7-cvwr-j2c6 · Severity: high · Ecosystem: go — Caddy: Windows `file_server` path authorization bypass via encoded backslash

OS Trackers for CVE-2026-52844

vendor priority summary link
debian not yet assigned CVE-2026-52844 not yet assigned priority: Debian including 1 source packages (caddy), 4 status rows across 4 suites (bookworm, forky, sid, trixie): open 4. https://security-tracker.debian.org/tracker/CVE-2026-52844
ubuntu medium CVE-2026-52844 medium priority: Ubuntu including 1 source packages (caddy), 5 status rows across 5 suites (jammy, noble, questing, resolute, upstream): needs-triage 4, DNE 1. https://ubuntu.com/security/CVE-2026-52844

Affected software / configurations for CVE-2026-52844

Vendor Product Version Raw CPE
caddyserver caddy < 2.11.4 cpe:2.3:a:caddyserver:caddy:*:*:*:*:*:*:*:*

References for CVE-2026-52844

cvelogic Threat Intelligence