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Medium, CVSS 5.9amended

Echo has a Static Middleware Double-Unescape Path Traversal

CVE-2026-118655GHSA-xwq5-6cqp-vx96

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (github.com/labstack/echo/v4 4.15.3; github.com/labstack/echo/v5 5.2.0), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
5.9 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
EPSS
  • CVE-2026-118655: 0.30% estimated exploitation activity in the next 30 days; percentile 23.16 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary Commit a9ede66a (PR #3006, issue #2599) silently fixed a path traversal vulnerability in the Echo web framework's static file middleware.

Vulnerability The static middleware double-unescaped URL paths. Go's net/http already decodes Request.URL.Path, but middleware/static.go unconditionally called url.PathUnescape() again: ```go // BEFORE (vulnerable) pathUnescape := true ``` This reassembled path traversal sequences from double-encoded input. An attacker could send GET /%2e%2e%2fsecret.txt or /..%252fsecret.txt and the double-unescape would produce ../secret.txt.

Fix ```go // AFTER (fixed) pathUnescape := false ``` The commit's test TestStatic_percentEncodedTraversalIsBlocked explicitly verifies traversal vectors are blocked.

Impact Arbitrary file read from server filesystem via percent-encoded path traversal.

References - Fix: https://github.com/labstack/echo/commit/a9ede66a - Issue: https://github.com/labstack/echo/issues/2599 - PR:…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from osv record GHSA-xwq5-6cqp-vx96

  2. Revision 1 · created ·

    Published from ghsa record GHSA-xwq5-6cqp-vx96

Agent brief

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# Patch Next advisory brief: CVE-2026-118655

Advisory: Echo has a Static Middleware Double-Unescape Path Traversal
IDs: CVE-2026-118655, GHSA-xwq5-6cqp-vx96
Record: https://patchnext.com/advisories/cve-2026-118655 (revision 2, source checked 29 Oct 2026, 06:45 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/labstack/echo/v4 4.15.3; github.com/labstack/echo/v5 5.2.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/labstack/echo/v4: affected < 4.15.3; fixed in 4.15.3
- Go github.com/labstack/echo/v5: affected < 5.2.0; fixed in 5.2.0

## Suggested inspection (read-only)
- Go github.com/labstack/echo/v4: check the installed version with your package manager.
- Go github.com/labstack/echo/v5: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/labstack/echo/v4, github.com/labstack/echo/v5.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-xwq5-6cqp-vx96 (GitHub-reviewed advisory GHSA-xwq5-6cqp-vx96 lists affected ranges: Go github.com/labstack/echo/v5 >=0 =0 <4.15.3)
- Verified: https://osv.dev/vulnerability/GHSA-xwq5-6cqp-vx96 (OSV record GHSA-xwq5-6cqp-vx96 lists affected ranges: Go github.com/labstack/echo/v5 >=0 =0 <4.15.3 (fixed))

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