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TI-2026-20833 Aliases CVE-2026-25766GHSA-pgvm-wxw2-hrv9

Echo has a Windows path traversal via backslash in middleware.Static default filesystem

Priority MEDIUM 63CWE-22Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Information disclosure
Confidentiality · integrity · availability
Low · None · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-22 and the CVSS impact.

Summary

Echo is a Go web framework. In versions 5.0.0 through 5.0.2 on Windows, Echo’s `middleware.Static` using the default filesystem allows path traversal via backslashes, enabling unauthenticated remote file read outside the static root. In `middleware/static.go`, the requested path is unescaped and normalized with `path.Clean` (URL semantics). `path.Clean` does not treat `\` as a path separator, so `..\` sequences remain in the cleaned path. The resulting path is then passed to `currentFS.Open(...)`. When the filesystem is left at the default (nil), Echo uses `defaultFS` which calls `os.Open` (`echo.go:792`). On Windows, `os.Open` treats `\` as a path separator and resolves `..\`, allowing traversal outside the static root. Version 5.0.3 fixes the issue.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00382 32nd percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed echo (labstack): 5.0.3github.com/labstack/echo/v5 (Go): 5.0.3

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
labstackecho5.0.0 to before 5.0.35.0.3Patch availableCNA
—github.com/labstack/echo/v5 (Go)5.0.0 to before 5.0.35.0.3Patch availableGHSA-pgvm-wxw2-hrv9
  • echo Vendorlabstack Affected 5.0.0 to before 5.0.3 Fixed in 5.0.3 Patch available CNA
  • github.com/labstack/echo/v5 (Go) Vendor— Affected 5.0.0 to before 5.0.3 Fixed in 5.0.3 Patch available GHSA-pgvm-wxw2-hrv9

CPE configurations NVD · 2

CPEVersionsRoleVendor
cpe:2.3:a:labstack:echo:*:*:*:*:*:go:*:*5.0.0 to before 5.0.3Vulnerablelabstack
cpe:2.3:o:microsoft:windows:-:*:*:*:*:*:*:*not specified by NVDRunning onMicrosoft
  • cpe:2.3:a:labstack:echo:*:*:*:*:*:go:*:* Versions 5.0.0 to before 5.0.3 Vulnerable ·labstack
  • cpe:2.3:o:microsoft:windows:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Microsoft

Remediation

  • Fix · CNA echo (labstack) Fixed in 5.0.3
  • Fix · GHSA-pgvm-wxw2-hrv9 github.com/labstack/echo/v5 (Go) Fixed in 5.0.3 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-25766
  2. 2026-10-03 Alias added: GHSA-pgvm-wxw2-hrv9

References

Exploit 1

Patch 2

Advisory 1

Other 2

  • TI-2022-18981 Labstack Echo v4.8.0 was discovered to contain an open redirect vulnerability via the… CVSS 3.1CRITICAL 9.6
  • TI-2020-18793 Directory traversal on Windows in github.com/labstack/echo/v4 CVSS 3.1MEDIUM 5.3

Sources

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