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TI-2026-37902 Aliases CVE-2026-52792GHSA-mm6c-5j6x-hq8m

Algernon: Server-side script source disclosure on Windows via NTFS filename

Priority HIGH 77CWE-69Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
—
Confidentiality · integrity · availability
High · None · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub.

Summary

Algernon is a small self-contained pure-Go web server. Prior to 1.17.9, Algernon on Windows selects a file handler in engine/handlers.go by calling filepath.Ext() without first rejecting NTFS-equivalent names such as x.lua::$DATA, x.lua., and x.lua . An unauthenticated client can append one of these suffixes to a public server-side script using the .lua, .tl, .po2, .amber, or .frm extension. The request path passes through URL2filename in utils/files.go, skips the renderer and execution cases, and reaches FilePage, os.Open, ReadAndLogErrors, and ToClient, while NTFS resolves the alias to the underlying script. The server consequently returns raw script source and can expose database credentials, API keys, and the SetCookieSecret value, which may permit forged session cookies. Linux and macOS hosts are not affected by this issue. This issue is fixed in version 1.17.9.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00628 50th percentileScored 2026-11-07
Fix Fixed algernon (xyproto): 1.17.9github.com/xyproto/algernon (Go): 1.17.9

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
xyprotoalgernonbefore 1.17.91.17.9Patch availableCNA
—github.com/xyproto/algernon (Go)before 1.17.91.17.9Patch availableGHSA-mm6c-5j6x-hq8m
  • algernon Vendorxyproto Affected before 1.17.9 Fixed in 1.17.9 Patch available CNA
  • github.com/xyproto/algernon (Go) Vendor— Affected before 1.17.9 Fixed in 1.17.9 Patch available GHSA-mm6c-5j6x-hq8m

Remediation

  • Fix · CNA algernon (xyproto) Fixed in 1.17.9
  • Fix · GHSA-mm6c-5j6x-hq8m github.com/xyproto/algernon (Go) Fixed in 1.17.9 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-52792
  2. 2026-10-03 Alias added: GHSA-mm6c-5j6x-hq8m
  3. 2026-10-29 EPSS moved to the 50th–90th percentile

References

Other 4

  • TI-2026-35564 Algernon: Host header path traversal in --domain mode reads files and runs Lua from parent dir CVSS 3.1HIGH 8.2
  • TI-2026-33460 Algernon: handler.lua discovery walks parent directories above the server root CVSS 3.1CRITICAL 9.0
  • TI-2026-33466 Algernon: Single-file mode unconditionally enables debug mode CVSS 3.1HIGH 7.5
  • TI-2026-34142 Algernon: Auto-refresh SSE event server sets Access-Control-Allow-Origin: * CVSS 3.1MEDIUM 4.3
  • TI-2026-34141 Algernon: Auto-refresh SSE event server binds to all interfaces by default on Linux/macOS CVSS 3.1MEDIUM 4.3
  • TI-2026-32026 Algernon: Path traversal file write via savein() CVSS 4.0HIGH 8.7
See all 7 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences