Service interruption via retained PUB metadata
Published May 28, 2021 · Updated Aug 3, 2024
Resource exhaustion in ZeroMQ libzmq before 4.3.3 allows remote attackers to interrupt service by sending crafted PUB messages. In src/xpub.cpp, PUB sockets do not process message metadata but retain a reference to it, so repeated messages accumulate unreleased memory. The attack requires a server endpoint without CURVE/ZAP authentication and can exhaust process memory until the service becomes unavailable.
Summary
What happened
Resource exhaustion in ZeroMQ libzmq before 4.3.3 allows remote attackers to interrupt service by sending crafted PUB messages. In src/xpub.cpp, PUB sockets do not process message metadata but retain a reference to it, so repeated messages accumulate unreleased memory. The attack requires a server endpoint without CURVE/ZAP authentication and can exhaust process memory until the service becomes unavailable.
The record
- CVE
- CVE-2021-20237
- Published
- May 28, 2021
- Updated
- Aug 3, 2024
- Vendor
- ZeroMQ
- Product
- libzmq
- Classifications
- CWE-401, CWE-400, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 28, 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?
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
- test_bind_null_fuzzer memory-leak 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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