CVE-2021-31870: Debian Linux

Critical severity, CVSS 9.8. EPSS: 2.1% chance of exploitation in the next 30 days.

An issue was discovered in klibc before 2.0.9. Multiplication in the calloc() function may result in an integer overflow and a subsequent heap buffer overflow.

Affected products

• Debian Debian Linux: version 9.0 only
• Klibc Project Klibc: before 2.0.9 (fixed in 2.0.9)

Published 2021-04-30. Last modified 2026-06-17.