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41Track*

Authorization bypass on case-insensitive filesystems in Algernon

xyproto algernon · CVE-2026-68548 ETK-2026-4312 EUVD-2026-124638 GHSA-VM84-8C4P-64HX
0 news outlets0 CERTs and agencies1 research labs

Assessment: Track*

SSVC decision points: exploitation poc, automatable yes, technical impact total, deployment low.

What is it?

Algernon is a small self-contained pure-Go web server. Prior to version 1.17.10, Algernon's URL-prefix authorization gate matches its protected prefixes (/admin, /repo, /data) with case-sensitive strings.HasPrefix, while the exact same raw req.URL.Path is later resolved against the filesystem. On case-insensitive filesystems (Windows NTFS — always; macOS APFS/HFS+ — default), a request for /Admin/secret.lua evades every protected-prefix check, falls through to the public-prefix accept branch, and then resolves on disk to admin/secret.lua. The result is an unauthenticated bypass of the /admin, /repo, and /data authorization boundary, enabling read (and, for Lua files, execution) of protected content. The permission system is active in the default configuration. This issue has been patched in version 1.17.10.

Evidence

Technical advisories1Detailed write-ups from security research teams

Exploitation

  • Exploit code published (not verified by us)
  • Exploited in the wild (confirmed by a source)
  • Listed as known exploited (CISA KEV)
CVSS
9.4
EPSS
–
First seen
6 h ago
Status
confirmed

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