CVE-2022-41721Network attack vector

Request smuggling via unread capped request body

Published Jan 13, 2023 · Updated Apr 4, 2025

Request smuggling in golang.org/x/net/http2/h2c before 0.1.1-0.20221104162952-702349b0e862 allows remote attackers to inject HTTP/2 requests. MaxBytesHandler leaves excess request-body bytes unread, and h2cHandler.ServeHTTP then parses those attacker-controlled bytes as subsequent HTTP/2 frames. The flaw is reachable only when an h2c handler is wrapped in MaxBytesHandler, and published scoring bounds the consequence to service interruption.

CVSS severity7.5
High
EPSS probability1.81%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Request smuggling in golang.org/x/net/http2/h2c before 0.1.1-0.20221104162952-702349b0e862 allows remote attackers to inject HTTP/2 requests. MaxBytesHandler leaves excess request-body bytes unread, and h2cHandler.ServeHTTP then parses those attacker-controlled bytes as subsequent HTTP/2 frames. The flaw is reachable only when an h2c handler is wrapped in MaxBytesHandler, and published scoring bounds the consequence to service interruption.

The record

CVE
CVE-2022-41721
Published
Jan 13, 2023
Updated
Apr 4, 2025
Vendor
Go
Product
golang.org/x/net/http2/h2c
Classifications
CWE-444, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 13, 2023CVE publishedPublication date reported by the CVE source.
  2. Apr 4, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0.0.0-20220524220425-1d687d428aca <0.1.1-0.20221104162952-702349b0e862

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Go · golang.org/x/net/http2/h2cversion=0.0.0-20220524220425-1d687d428aca <0.1.1-0.20221104162952-702349b0e862

Published CVSS scores

7.5GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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