CVE-2021-20235
Published: 01 April 2021
Summary
CVE-2021-20235 is a high-severity Classic Buffer Overflow (CWE-120) vulnerability in Zeromq Libzmq. Its CVSS base score is 8.1 (High).
Operationally, ranked in the top 8.6% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2021-7674
Vulnerability details
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…
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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.
- CWE(s)
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Platform-independent managed code eliminates the need for unchecked native buffer copies that are the root cause of classic buffer overflows.
Out-of-bounds writes that corrupt control flow or inject shellcode are rendered non-executable by the same memory protections.