Client IP disclosure via cloned header nilness loss
Published Aug 9, 2022 · Updated Mar 6, 2026
Information exposure in Go standard library net/http before 1.17.12 and 1.18.0 through 1.18.3 allows remote attackers to expose client IP addresses. Header.Clone converts a nil X-Forwarded-For slice into a non-nil zero-length slice, so ReverseProxy.ServeHTTP treats the header as unset and writes the request's client IP into it. Exposure requires an application to pass ServeHTTP a request whose original Header map already contains a nil X-Forwarded-For value.
Summary
What happened
Information exposure in Go standard library net/http before 1.17.12 and 1.18.0 through 1.18.3 allows remote attackers to expose client IP addresses. Header.Clone converts a nil X-Forwarded-For slice into a non-nil zero-length slice, so ReverseProxy.ServeHTTP treats the header as unset and writes the request's client IP into it. Exposure requires an application to pass ServeHTTP a request whose original Header map already contains a nil X-Forwarded-For value.
The record
- CVE
- CVE-2022-32148
- Published
- Aug 9, 2022
- Updated
- Mar 6, 2026
- Vendor
- Go standard library
- Product
- net/http
- Classifications
- T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 9, 2022CVE publishedPublication date reported by the CVE source.
- Mar 6, 2026Record 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 <1.17.12
- Affected versionversion=1.18.0-0 <1.18.4
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
- Go issue 53423 proof of conceptproof of concept · unverified
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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