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TI-2026-32026 Aliases CVE-2026-43982

Algernon: Path traversal file write via savein()

Priority MEDIUM 44CWE-22Published · Updated

Key facts

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

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

Summary

Algernon is a small self-contained pure-Go web server. Prior to 1.17.6, uploadedFileSaveIn() in lua/upload/upload.go uses filepath.Join() with the caller-supplied directory but performs no boundary check after joining. A directory of ../../../tmp resolves cleanly to /tmp, outside the web root. This vulnerability is fixed in 1.17.6.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00344 28th percentileScored 2026-11-07
Fix Fixed algernon (xyproto): 1.17.6

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
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 1.17.61.17.6Patch availableCNA
  • algernon Vendorxyproto Affected before 1.17.6 Fixed in 1.17.6 Patch available CNA

Remediation

  • Fix · CNA algernon (xyproto) Fixed in 1.17.6

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-43982

References

Other 2

  • TI-2026-37902 Algernon: Server-side script source disclosure on Windows via NTFS filename CVSS 4.0HIGH 8.7
  • 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
See all 7 →

Sources

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