HTTP header injection via trailing newline acceptance
Published Apr 17, 2023 · Updated Feb 13, 2025
Improper header validation in Guzzle PSR-7 before 1.9.1 and 2.0.0 through 2.4.4 allows remote attackers to inject HTTP headers. MessageTrait::assertHeader and assertValue use end-anchored regular expressions that accept a trailing line feed, allowing newline-bearing names or values. Exploitation requires an application to place attacker-controlled header data into a PSR-7 message and forward it to a server that treats two line feeds as the header terminator, enabling injected headers to alter downstream requests or responses.
Summary
What happened
Improper header validation in Guzzle PSR-7 before 1.9.1 and 2.0.0 through 2.4.4 allows remote attackers to inject HTTP headers. MessageTrait::assertHeader and assertValue use end-anchored regular expressions that accept a trailing line feed, allowing newline-bearing names or values. Exploitation requires an application to place attacker-controlled header data into a PSR-7 message and forward it to a server that treats two line feeds as the header terminator, enabling injected headers to alter downstream requests or responses.
The record
- CVE
- CVE-2023-29197
- Published
- Apr 17, 2023
- Updated
- Feb 13, 2025
- Vendor
- Guzzle
- Product
- Guzzle PSR-7
- Classifications
- CWE-436
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 17, 2023CVE publishedPublication date reported by the CVE source.
- Feb 13, 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?
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- Affected versionversion=< 1.9.1
- Affected versionversion=>= 2.0.0, < 2.4.5
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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