Client crash via unfinished-message memory leak
Published Apr 1, 2021 · Updated Aug 3, 2024
Uncontrolled resource consumption in ZeroMQ libzmq before 4.3.3 allows remote attackers to crash clients via malicious servers. When src/pipe.cpp processes a delimiter for an inactive pipe that retains an unfinished message, it drops the pipe reference without rolling back the message and leaks its allocation. Exploitation requires an unprotected client to be induced to connect to multiple malicious or compromised servers; repeated leaks exhaust memory and terminate the client.
Summary
What happened
Uncontrolled resource consumption in ZeroMQ libzmq before 4.3.3 allows remote attackers to crash clients via malicious servers. When src/pipe.cpp processes a delimiter for an inactive pipe that retains an unfinished message, it drops the pipe reference without rolling back the message and leaks its allocation. Exploitation requires an unprotected client to be induced to connect to multiple malicious or compromised servers; repeated leaks exhaust memory and terminate the client.
The record
- CVE
- CVE-2021-20234
- Published
- Apr 1, 2021
- Updated
- Aug 3, 2024
- Vendor
- ZeroMQ
- Product
- libzmq
- Classifications
- CWE-401, CWE-400, T1499
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 1, 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=zeromq 4.3.3
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
- Upstream malicious-server fuzz reproducerproof of concept · demonstrated
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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