CVE-2021-20235
8.1 · HIGHOverview
CVE-2021-20235 is a high-severity vulnerability affecting zeromq libzmq. It was published on April 1, 2021 and has a CVSS 3.1 base score of 8.1 (HIGH).
This vulnerability has a CVSS 3.1 base score of 8.1, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
There's a flaw in the zeromq server in versions before 4.3.3 in src/decoder_allocators.hpp. The decoder static allocator could have its sized changed, but the buffer would remain the same as it is a static buffer. A remote, unauthenticated attacker who sends a crafted request to the zeromq server could trigger a buffer overflow WRITE of arbitrary data if CURVE/ZAP authentication is not enabled. The greatest impact of this flaw is to application availability, data integrity, and confidentiality.
Remediation
Check the references section for vendor advisories and patches from zeromq. Update libzmq to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| zeromq | libzmq | >= 4.2.0, < 4.3.3 | Affected |
Frequently Asked Questions
What is CVE-2021-20235?
CVE-2021-20235 is a high-severity vulnerability affecting zeromq libzmq. It was published on April 1, 2021 and has a CVSS 3.1 base score of 8.1 (HIGH).
How severe is CVE-2021-20235?
This vulnerability has a CVSS 3.1 base score of 8.1, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2021-20235?
Check the references section for vendor advisories and patches from zeromq. Update libzmq to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2021-20235?
CyberStrike's AI-powered security agents can automatically detect CVE-2021-20235 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
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