Request smuggling via stale Transfer-Encoding state
Published Feb 11, 2021 · Updated Aug 3, 2024
HTTP request smuggling in affected Hyper releases allows remote attackers to desynchronize proxied HTTP/1.1 connections. In src/proto/h1/role.rs, the server parser failed to clear is_te_chunked when a later Transfer-Encoding header did not end in chunked, so an illegal request was accepted as chunked. Exploitation requires server mode, HTTP/1.1, and an upstream proxy that parses the request boundary differently; the resulting stream desynchronization lets attacker-controlled bytes become a subsequent request.
Summary
What happened
HTTP request smuggling in affected Hyper releases allows remote attackers to desynchronize proxied HTTP/1.1 connections. In src/proto/h1/role.rs, the server parser failed to clear is_te_chunked when a later Transfer-Encoding header did not end in chunked, so an illegal request was accepted as chunked. Exploitation requires server mode, HTTP/1.1, and an upstream proxy that parses the request boundary differently; the resulting stream desynchronization lets attacker-controlled bytes become a subsequent request.
The record
- CVE
- CVE-2021-21299
- Published
- Feb 11, 2021
- Updated
- Aug 3, 2024
- Vendor
- Hyperium
- Product
- Hyper
- Classifications
- CWE-444, CAPEC-33, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 11, 2021CVE publishedPublication date reported by the CVE source.
- Aug 3, 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=< 0.13.10
- Affected versionversion=>= 0.14.0, < 0.14.3
What conditions does exploitation require?
What is affected?
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
- Maintainer malformed Transfer-Encoding request exampleproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
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