HTTP request smuggling via unsanitized request URI
Published Dec 16, 2025 · Updated Dec 16, 2025
CRLF injection in Netty before 4.1.129.Final and 4.2.0.Alpha1 through 4.2.7.Final allows remote attackers to smuggle HTTP requests. HttpRequestEncoder writes the URI directly into the HTTP request line as UTF-8 without rejecting or neutralizing carriage returns and line feeds. Exploitation requires an application to pass attacker-controlled, unsanitized URI data to the encoder; injected line breaks can create additional requests.
Summary
What happened
CRLF injection in Netty before 4.1.129.Final and 4.2.0.Alpha1 through 4.2.7.Final allows remote attackers to smuggle HTTP requests. HttpRequestEncoder writes the URI directly into the HTTP request line as UTF-8 without rejecting or neutralizing carriage returns and line feeds. Exploitation requires an application to pass attacker-controlled, unsanitized URI data to the encoder; injected line breaks can create additional requests.
The record
- CVE
- CVE-2025-67735
- Published
- Dec 16, 2025
- Updated
- Dec 16, 2025
- Vendor
- The Netty Project
- Product
- Netty
- Classifications
- CWE-93
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Dec 16, 2025CVE publishedPublication date reported by the CVE source.
- Dec 16, 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.
- Affected versionversion=< 4.1.129.Final
- Affected versionversion=>= 4.2.0.Alpha1, < 4.2.8.Final
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
- GHSA-84h7-rjj3-6jx4 embedded reproducerproof of concept · demonstrated
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Technologies
Your stack
See the directory against your own environment.
Your stack
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