Access-control bypass via ambiguous IPv4 parsing
Published Aug 7, 2021 · Updated Aug 3, 2024
Improper IP-address validation in Go before 1.17 allows remote attackers to bypass IP-based access controls with crafted IPv4 input. net.ParseIP and net.ParseCIDR accept octets with leading zeros as decimal, while downstream libc-based consumers can interpret the same text as octal and reach a different address. Exploitation requires a program to validate attacker-controlled address text with the Go parser and then pass the original text to a component whose interpretation differs.
Summary
What happened
Improper IP-address validation in Go before 1.17 allows remote attackers to bypass IP-based access controls with crafted IPv4 input. net.ParseIP and net.ParseCIDR accept octets with leading zeros as decimal, while downstream libc-based consumers can interpret the same text as octal and reach a different address. Exploitation requires a program to validate attacker-controlled address text with the Go parser and then pass the original text to a component whose interpretation differs.
The record
- CVE
- CVE-2021-29923
- Published
- Aug 7, 2021
- Updated
- Aug 3, 2024
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- Unavailable
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 7, 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?
What conditions does exploitation require?
What is affected?
Affected products and versions are unavailable in this record.
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
No sourced classifications are available.
Public exploit references
- Leading-zero ParseCIDR proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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