CVE-2021-3121: Golang Protobuf

High severity, CVSS 8.6. EPSS: 3.4% chance of exploitation in the next 30 days.

An issue was discovered in GoGo Protobuf before 1.3.2. plugin/unmarshal/unmarshal.go lacks certain index validation, aka the "skippy peanut butter" issue.

Affected products

• Golang Protobuf: before 1.3.2 (fixed in 1.3.2)
• Hashicorp Consul: before 1.8.15 (fixed in 1.8.15); from 1.9.0, before 1.9.9 (fixed in 1.9.9); from 1.10.0, before 1.10.2 (fixed in 1.10.2)

Published 2021-01-11. Last modified 2026-06-17.