AUGUST 4, 2026
Live Feed
Back to database
Case File

CVE-2021-20235

HIGH · CVSS 8.1 EPSS 43.86% Public Exploit

Source: NVD + CISA KEV + EPSS (historical backfill) · Published 2021-04-01 · Last synced 2026-08-04

CyberRota Analysis

This is a high severity vulnerability with a CVSS score of 8.1. Public exploit code or proof-of-concept references have been detected in its references. Its EPSS score suggests a 43.9% probability of exploitation in the next 30 days. It may be remotely exploitable. Exploitation may require the attacker to be authenticated.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

GitHub PoC Links

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2021-20235
Severity
HIGH
CVSS
8.1
EPSS
43.86%

Original NVD 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.

Related CVEs

Other vulnerabilities affecting the same vendor(s)