Authentication bypass via unconditional connection tunneling
Published Jun 10, 2021 · Updated Aug 5, 2024
HTTP request smuggling in Apache HTTP Server 2.4.6 through 2.4.46 allows remote attackers to bypass request validation and access controls. On a mod_proxy_wstunnel route, the proxy tunnels the connection even when the origin does not accept the protocol upgrade, so later requests avoid normal HTTP processing. Exposure requires a WebSocket proxy route whose origin does not necessarily return a 101 response; subsequent requests can reach the origin without configured validation, authentication, or authorization.
Summary
What happened
HTTP request smuggling in Apache HTTP Server 2.4.6 through 2.4.46 allows remote attackers to bypass request validation and access controls. On a mod_proxy_wstunnel route, the proxy tunnels the connection even when the origin does not accept the protocol upgrade, so later requests avoid normal HTTP processing. Exposure requires a WebSocket proxy route whose origin does not necessarily return a 101 response; subsequent requests can reach the origin without configured validation, authentication, or authorization.
The record
- CVE
- CVE-2019-17567
- Published
- Jun 10, 2021
- Updated
- Aug 5, 2024
- Vendor
- The Apache Software Foundation
- Product
- Apache HTTP Server
- Classifications
- CWE-444, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 10, 2021CVE publishedPublication date reported by the CVE source.
- Aug 5, 2024Record 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.
- Affected versionversion=2.4.10
- Affected versionversion=2.4.12
- Affected versionversion=2.4.16
- Affected versionversion=2.4.17
- Affected versionversion=2.4.18
- Affected versionversion=2.4.20
- Affected versionversion=2.4.23
- Affected versionversion=2.4.25
- Affected versionversion=2.4.26
- Affected versionversion=2.4.27
- Affected versionversion=2.4.28
- Affected versionversion=2.4.29
- Affected versionversion=2.4.33
- Affected versionversion=2.4.34
- Affected versionversion=2.4.35
- Affected versionversion=2.4.37
- Affected versionversion=2.4.38
- Affected versionversion=2.4.39
- Affected versionversion=2.4.41
- Affected versionversion=2.4.43
- Affected versionversion=2.4.46
- Affected versionversion=2.4.6
- Affected versionversion=2.4.7
- Affected versionversion=2.4.9
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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