---
id: CVE-2022-21221
aliases:
  - GHSA-fx95-883v-4q4h
  - GO-2022-0355
  - SNYK-GOLANG-GITHUBCOMVALYALAFASTHTTP-2407866
title: Path traversal in github.com/valyala/fasthttp
summary: Path traversal in github.com/valyala/fasthttp
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'
vendor: valyala
product: github.com/valyala/fasthttp
ecosystem: go
affected:
  - github.com/valyala/fasthttp < 1.34.0
patched:
  - github.com/valyala/fasthttp 1.34.0
published: '2022-03-18'
updated: '2026-07-08'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-fx95-883v-4q4h'
references:
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2022-21221'
  - url: 'https://github.com/valyala/fasthttp/issues/1226'
  - url: >-
      https://github.com/valyala/fasthttp/commit/15262ecf3c602364639d465daba1e7f3604d00e8
  - url: >-
      https://github.com/valyala/fasthttp/commit/6b5bc7bb304975147b4af68df54ac214ed2554c1
  - url: 'https://github.com/valyala/fasthttp'
  - url: 'https://github.com/valyala/fasthttp/releases/tag/v1.34.0'
  - url: 'https://pkg.go.dev/vuln/GO-2022-0355'
  - url: 'https://snyk.io/vuln/SNYK-GOLANG-GITHUBCOMVALYALAFASTHTTP-2407866'
tags:
  - osv
  - go
epss: 0.02496
epssPercentile: 0.84016
ingestedAt: '2026-07-09T18:56:36.364Z'
---

## Overview

The package github.com/valyala/fasthttp before 1.34.0 is vulnerable to Directory Traversal via the ServeFile function, due to improper sanitization. It is possible to be exploited by using a backslash %5c character in the path. **Note:** This security issue impacts Windows users only.

## Affected packages

- `github.com/valyala/fasthttp < 1.34.0`

## Remediation

Upgrade to a patched release:

- `github.com/valyala/fasthttp 1.34.0`