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Algernon: Case-insensitive filesystem lets unauthenticated requests bypass /admin,/repo,/data permission-prefix gate
Not on CISA's list of exploited flaws, and not in the news we track.
CVE-2026-68548Critical9.4
Black Shard's team can check your exposure to CVE-2026-68548 and take the fix off your plate.
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.
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Severity
9.4of 10, critical
Updated 13 Nov 2026, 12:04 UTC, 31 of 36 sources answering.
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