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Medium, CVSS 6.1

Async-h1 request smuggling possible with long unread bodies

CVE-2020-36202GHSA-c8rq-crxj-mj9m

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (async-h1 2.3.0), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • crates.io async-h1

    Affected
    < 2.3.0
    Fixed in
    2.3.0

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
6.1 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
EPSS
  • CVE-2020-36202: 0.83% estimated exploitation activity in the next 30 days; percentile 57.44 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

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.

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from ghsa record GHSA-c8rq-crxj-mj9m

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2020-36202

Advisory: Async-h1 request smuggling possible with long unread bodies
IDs: CVE-2020-36202, GHSA-c8rq-crxj-mj9m
Record: https://patchnext.com/advisories/cve-2020-36202 (revision 1, source checked 26 Oct 2026, 15:33 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: async-h1 2.3.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io async-h1: affected < 2.3.0; fixed in 2.3.0

## Suggested inspection (read-only)
- crates.io async-h1: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on async-h1.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-c8rq-crxj-mj9m (GitHub-reviewed advisory GHSA-c8rq-crxj-mj9m lists affected ranges: crates.io async-h1 >=0 <2.3.0)

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