CVE-2020-36202: Async h1 Async-h1 Request Smuggling Possible With Vulnerability

MODERATE
Advisory Identifier: GHSA-c8rq-crxj-mj9m
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CVSS 6.1
CWE-79
Published
Advisory Summary

CVE-2020-36202 is a MODERATE (CVSS 6.1) async-h1 request smuggling possible with vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Async h1 libraries in the crates.io ecosystem. The issue involves async-h1 request smuggling possible with long unread bodies. Remediation is available by upgrading affected packages to version 2.3.0.

CVE-2020-36202 at a Glance

CVE Identifier CVE-2020-36202
GHSA Identifier GHSA-c8rq-crxj-mj9m
Severity MODERATE
CVSS v3.1 Base Score 6.1
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Async h1
Package Ecosystem crates.io
Published Date
Last Updated

Security Impact

CVSS: 6.1

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:R/S:C/C:L/I:L/A:N).

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

How to Fix CVE-2020-36202

To remediate this vulnerability, upgrade all affected Async h1 dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

async-h1 fixed: 2.3.0 
Upgrade async-h1 to 2.3.0
Verify Direct and Transitive Dependencies

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

inspect dependencies for async-h1

How to Check if You Are Affected

To determine whether your application is affected by CVE-2020-36202, inspect your project dependencies for Async h1:

inspect dependencies for async-h1

Analyze the terminal output to locate any version of Async h1 in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.3.0), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), where the product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. In Async h1, 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

An issue was discovered in the async-h1 crate before 2.3.0 for Rust. Request smuggling can occur when used behind a reverse proxy.

CVE-2020-36202 Affected Async h1 Versions

1 component(s)
Fixed Versions:
2.3.0
Product / Package Ecosystem Affected Versions Fixed Version
async-h1
 crates.io
< 2.3.0
2.3.0

References

NVD — CVE-2020-36202 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-36202
Async h1 Source Repository REPOSITORY
https://github.com/http-rs/async-h1
Async h1 Release RELEASE
https://github.com/http-rs/async-h1/releases/tag/v2.3.0
rustsec.org/advisories/rustsec-... WEB
https://rustsec.org/advisories/RUSTSEC-2020-0093.html

Frequently Asked Questions

What is CVE-2020-36202?
CVE-2020-36202 is a security vulnerability in Async h1 involving Async-h1 request smuggling possible with long unread bodies under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Async h1 versions are affected?
Affected versions include releases prior to 2.3.0 across affected packages: async-h1.
What version fixes CVE-2020-36202?
Upgrading to 2.3.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is async-h1 affected?
Yes, async-h1 is affected in releases prior to 2.3.0. Upgrade your dependency to 2.3.0 or later.
What is the CVSS score of CVE-2020-36202?
CVE-2020-36202 has a CVSS v3.1 base score of 6.1 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
What CWE is associated with CVE-2020-36202?
CVE-2020-36202 is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.).
How can I check crates.io dependencies for CVE-2020-36202?
Run the dependency tree command: 'inspect dependencies for async-h1'. 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-c8rq-crxj-mj9m",
  "modified" : "2022-06-16T23:45:25Z",
  "published" : "2022-05-24T17:40:15Z",
  "aliases" : [ "CVE-2020-36202" ],
  "summary" : "Async-h1 request smuggling possible with long unread bodies",
  "details" : "An issue was discovered in the async-h1 crate before 2.3.0 for Rust. Request smuggling can occur when used behind a reverse proxy.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "async-h1"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.3.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-36202"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/http-rs/async-h1"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/http-rs/async-h1/releases/tag/v2.3.0"
  }, {
    "type" : "WEB",
    "url" : "https://rustsec.org/advisories/RUSTSEC-2020-0093.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2022-06-16T23:45:25Z",
    "nvd_published_at" : "2021-01-26T18:15:00Z"
  }
}