CVE-2021-32715

What it is

hyper is an HTTP library for rust. hyper's HTTP/1 server code had a flaw that incorrectly parses and accepts requests with a `Content-Length` header with a prefixed plus sign, when it should have been rejected as illegal. This combined with an upstream HTTP proxy that doesn't parse such `Content-Length` headers, but forwards them, can result in "request smuggling" or "desync attacks". The flaw exists in all prior versions of hyper prior to 0.14.10, if built with `rustc` v1.5.0 or newer. The vulnerability is patched in hyper version 0.14.10. Two workarounds exist: One may reject requests manually that contain a plus sign prefix in the `Content-Length` header or ensure any upstream proxy handles `Content-Length` headers with a plus sign prefix.

At a glance

Exploitability

Can be exploited over the network without logging in, but needs a user to act. Limited direct impact.

Exploit odds

1.1% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2021-07-07 20:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 03:53 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 1.1% in the next 30 days (EPSS).
• Severity: 3.1 LOW (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2021-07-07 20:15 UTC

Last modified

2026-06-17 03:53 UTC

Exploit probability

1.1% · EPSS, next 30 days

Weakness

CWE-444

Record status

Modified

Affected

• Hyper < 0.14.10

Attack profile CVSS 3.1 · 3.1

Attack vector

Network

Complexity

High

Privileges needed

None

User interaction

Required

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-32715.md and follow it. Check whether this project is affected by CVE-2021-32715. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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