CVE-2026-102657 (GCVE-0-2026-102657)

Vulnerability from cvelistv5 – Published: 2026-11-06 20:49 – Updated: 2026-11-06 20:49
VLAI
Title
esm.sh: web.NewHandler allows arbitrary file read via encoded dot-segment path traversal
Summary
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
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CWE
  • CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Assigner
GitHub_M CNA
References
Impacted products
Vendor Product Version
esm-dev esm.sh Affected: < 137_7
Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "esm.sh",
          "vendor": "esm-dev",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 137_7"
            }
          ]
        }
      ],
      "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\u0027s 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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-22",
              "description": "CWE-22: Improper Limitation of a Pathname to a Restricted Directory (\u0027Path Traversal\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-11-06T20:49:28.708Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/esm-dev/esm.sh/security/advisories/GHSA-g3c2-rjq2-c763",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/esm-dev/esm.sh/security/advisories/GHSA-g3c2-rjq2-c763"
        },
        {
          "name": "https://github.com/esm-dev/esm.sh/pull/1376",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/esm-dev/esm.sh/pull/1376"
        },
        {
          "name": "https://github.com/esm-dev/esm.sh/commit/468b6b2a4b4dfec334cf6b33b01fcd4e5cd93bed",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/esm-dev/esm.sh/commit/468b6b2a4b4dfec334cf6b33b01fcd4e5cd93bed"
        },
        {
          "name": "https://github.com/esm-dev/esm.sh/commit/fc3b345e73aeaa0b7a05b6f27d91c05fdf5f9b53",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/esm-dev/esm.sh/commit/fc3b345e73aeaa0b7a05b6f27d91c05fdf5f9b53"
        },
        {
          "name": "https://github.com/esm-dev/esm.sh/releases/tag/v137_7",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/esm-dev/esm.sh/releases/tag/v137_7"
        }
      ],
      "source": {
        "advisory": "GHSA-g3c2-rjq2-c763",
        "discovery": "UNKNOWN"
      },
      "title": "esm.sh: web.NewHandler allows arbitrary file read via encoded dot-segment path traversal"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-102657",
    "datePublished": "2026-11-06T20:49:28.708Z",
    "dateReserved": "2026-09-29T15:56:02.101Z",
    "dateUpdated": "2026-11-06T20:49:28.708Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.

Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

JSON

Loading timeline…




    Related by attack behaviour

    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.