CVE-2021-32715

Lenient Parsing of Content-Length Header When Prefixed with Plus Sign

MEDIUM
5.3
CVSS Score
Published: July 7, 2021 at 08:05 PM UTC
Updated: June 17, 2026 at 03:53 AM UTC
2 products affected across 2 vendorsHyperHyper

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Severity
MEDIUM5.3
Exploit prediction
EPSS 1%

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 0.14.10
Affected range stops below 0.14.10, so it looks safe — our inference, not a vendor statement
v < 0.14.10
Affected range stops below 0.14.10, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-444

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