CVE-2026-102657

Full vulnerability record from the local CVENow database.

Description

esm.sh is a no-build content delivery network (CDN) for web development. Prior to server version 137_7, the documented web.NewHandler static file server in web/handler.go joins the URL-decoded r.URL.Path with Config.AppDir without verifying that the result remains inside the configured application directory. URL-encoded dot segments such as %2e%2e bypass the plain traversal redirect performed by Go's ServeMux, allowing an unauthenticated remote attacker to make the server open and return files outside Config.AppDir that are readable by the server process. The confirmed impact is file disclosure only, and the issue is reachable with Dev disabled. This issue is fixed in server version 137_7.

Severity

HIGH

CVSS score

7.5 (v3.1)

Vulnerability status

Deferred

Source identifier

[email protected]

Published

2026-11-06 21:17:05.863000

Last modified

2026-11-06 21:17:06.027000

View original CVE JSON

{
  "id": "CVE-2026-102657",
  "sourceIdentifier": "[email protected]",
  "published": "2026-11-06T21:17:05.863",
  "lastModified": "2026-11-06T21:17:06.027",
  "vulnStatus": "Deferred",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "esm.sh is a no-build content delivery network (CDN) for web development. Prior to server version 137_7, the documented web.NewHandler static file server in web/handler.go joins the URL-decoded r.URL.Path with Config.AppDir without verifying that the result remains inside the configured application directory. URL-encoded dot segments such as %2e%2e bypass the plain traversal redirect performed by Go's ServeMux, allowing an unauthenticated remote attacker to make the server open and return files outside Config.AppDir that are readable by the server process. The confirmed impact is file disclosure only, and the issue is reachable with Dev disabled. This issue is fixed in server version 137_7."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "esm-dev",
          "product": "esm.sh",
          "versions": [
            {
              "version": "< 137_7",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "NONE",
          "availabilityImpact": "NONE"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Primary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-22"
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://github.com/esm-dev/esm.sh/commit/468b6b2a4b4dfec334cf6b33b01fcd4e5cd93bed",
      "source": "[email protected]"
    },
    {
      "url": "https://github.com/esm-dev/esm.sh/commit/fc3b345e73aeaa0b7a05b6f27d91c05fdf5f9b53",
      "source": "[email protected]"
    },
    {
      "url": "https://github.com/esm-dev/esm.sh/pull/1376",
      "source": "[email protected]"
    },
    {
      "url": "https://github.com/esm-dev/esm.sh/releases/tag/v137_7",
      "source": "[email protected]"
    },
    {
      "url": "https://github.com/esm-dev/esm.sh/security/advisories/GHSA-g3c2-rjq2-c763",
      "source": "[email protected]"
    }
  ]
}