Remote code execution via predictable Erlang cookie
Published Jan 25, 2022 · Updated Apr 23, 2025
Weak cookie generation in Zulip Server before 4.9 allows remote attackers to execute code and read message traffic through RabbitMQ. During initial installation, RabbitMQ keeps distribution port 25672 exposed and protects it with an automatically generated 20-character cookie containing about 20 bits of practical entropy. Exploitation requires network access to that port before RabbitMQ's first restart and yields code execution as the rabbitmq user plus disclosure of messages transiting the broker.
Summary
What happened
Weak cookie generation in Zulip Server before 4.9 allows remote attackers to execute code and read message traffic through RabbitMQ. During initial installation, RabbitMQ keeps distribution port 25672 exposed and protects it with an automatically generated 20-character cookie containing about 20 bits of practical entropy. Exploitation requires network access to that port before RabbitMQ's first restart and yields code execution as the rabbitmq user plus disclosure of messages transiting the broker.
The record
- CVE
- CVE-2021-43799
- Published
- Jan 25, 2022
- Updated
- Apr 23, 2025
- Vendor
- Zulip
- Product
- Zulip
- Classifications
- CWE-338, T1110.001, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jan 25, 2022CVE publishedPublication date reported by the CVE source.
- Apr 23, 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=< 4.9
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
- erl-matter Erlang distribution toolingfunctional · demonstrated
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Technologies
Your stack
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Your stack
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