CVE-2026-15074: @fastify/static Path Traversal Vulnerability

HIGH
Advisory Identifier: GHSA-83w8-p2f5-377r
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CVSS 7.5
CWE-22
Published
Advisory Summary

CVE-2026-15074 is a HIGH (CVSS 7.5) path traversal vulnerability (CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')) affecting @fastify/static libraries in the npm ecosystem. The issue involves @fastify/static vulnerable to route guard bypass via path traversal. Remediation is available by upgrading affected packages to version 10.1.1.

CVE-2026-15074 at a Glance

CVE Identifier CVE-2026-15074
GHSA Identifier GHSA-83w8-p2f5-377r
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Affected Product @fastify/static
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2026-15074

To remediate this vulnerability, upgrade all affected @fastify/static dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

@fastify/static fixed: 10.1.1 
npm install @fastify/static@10.1.1
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls @fastify/static

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-15074, inspect your project dependencies using npm:

npm ls @fastify/static

Analyze the terminal output to locate any version of @fastify/static in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 10.1.1), your application is affected.

Note: The npm ls @fastify/static command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'), where the product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. In @fastify/static, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact `@fastify/static` is vulnerable to a bypass of route-based middleware and guards via non-leading `..` and `%2E%2E` path segments. `find-my-way` does not normalize `..` when matching routes, so a request such as `/foo/../deep/secret.txt` matches the static plugin's catch-all instead of the guarded `/deep/*`. The `getPathnameForSend` helper introduced by the fix for [GHSA-x428-ghpx-8j92](https://github.com/fastify/fastify-static/security/advisories/GHSA-x428-ghpx-8j92) only guards against the `%2F` variant; `..` and `%2E%2E` survive the `decodeURI` + `encodeURI` round-trip and are then collapsed away by `@fastify/send`'s `path.normalize` before its own traversal guard runs. Applications that rely on route-based middleware or guards to protect files served by `@fastify/static` can be bypassed with non-leading dot-dot path segments. ### Patches Upgrade to `@fastify/static` 10.1.1. ### Workarounds Do not use route-based middlewares or guards to protect files served by `@fastify/static`.

CVE-2026-15074 Affected @fastify/static Versions

1 component(s)
Fixed Versions:
10.1.1
Product / Package Ecosystem Affected Versions Fixed Version
@fastify/static
npm/@fastify/static
npm
< 10.1.1
10.1.1

References

GitHub Advisory / Wiki ADVISORY
https://github.com/fastify/fastify-static/security/advisories/GHSA-83w8-p2f5-377r
NVD — CVE-2026-15074 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-15074
Security Fix Commit FIX COMMIT
https://github.com/fastify/fastify-static/commit/db4276f846ba56b21f93768cd6636ee5e2fc58b1
@fastify/static Security Information SECURITY
https://cna.openjsf.org/security-advisories.html
@fastify/static Source Repository REPOSITORY
https://github.com/fastify/fastify-static
@fastify/static Release RELEASE
https://github.com/fastify/fastify-static/releases/tag/v10.1.1

Frequently Asked Questions

What is CVE-2026-15074?
CVE-2026-15074 is a security vulnerability in @fastify/static involving @fastify/static vulnerable to route guard bypass via path traversal under CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal').
Which @fastify/static versions are affected?
Affected versions include releases prior to 10.1.1 across affected packages: @fastify/static.
What version fixes CVE-2026-15074?
Upgrading to 10.1.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is @fastify/static affected?
Yes, @fastify/static is affected in releases prior to 10.1.1. Upgrade your dependency to 10.1.1 or later.
What is the CVSS score of CVE-2026-15074?
CVE-2026-15074 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.
What CWE is associated with CVE-2026-15074?
CVE-2026-15074 is classified under CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') (The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.).
How can I check npm dependencies for CVE-2026-15074?
Run the dependency tree command: 'npm ls @fastify/static'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-83w8-p2f5-377r",
  "modified" : "2026-07-24T16:43:21Z",
  "published" : "2026-07-24T16:43:21Z",
  "aliases" : [ "CVE-2026-15074" ],
  "summary" : "@fastify/static vulnerable to route guard bypass via path traversal",
  "details" : "### Impact\n\n`@fastify/static` is vulnerable to a bypass of route-based middleware and guards via non-leading `..` and `%2E%2E` path segments. `find-my-way` does not normalize `..` when matching routes, so a request such as `/foo/../deep/secret.txt` matches the static plugin's catch-all instead of the guarded `/deep/*`. The `getPathnameForSend` helper introduced by the fix for [GHSA-x428-ghpx-8j92](https://github.com/fastify/fastify-static/security/advisories/GHSA-x428-ghpx-8j92) only guards against the `%2F` variant; `..` and `%2E%2E` survive the `decodeURI` + `encodeURI` round-trip and are then collapsed away by `@fastify/send`'s `path.normalize` before its own traversal guard runs.\n\nApplications that rely on route-based middleware or guards to protect files served by `@fastify/static` can be bypassed with non-leading dot-dot path segments.\n\n### Patches\n\nUpgrade to `@fastify/static` 10.1.1.\n\n### Workarounds\n\nDo not use route-based middlewares or guards to protect files served by `@fastify/static`.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@fastify/static"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "10.1.1"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 10.1.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/fastify/fastify-static/security/advisories/GHSA-83w8-p2f5-377r"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-15074"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/fastify/fastify-static/commit/db4276f846ba56b21f93768cd6636ee5e2fc58b1"
  }, {
    "type" : "WEB",
    "url" : "https://cna.openjsf.org/security-advisories.html"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/fastify/fastify-static"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/fastify/fastify-static/releases/tag/v10.1.1"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-22" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-24T16:43:21Z",
    "nvd_published_at" : "2026-07-23T04:16:31Z"
  }
}