What’s Vulnerable › Vulnerabilities

CVE-2021-31870

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-04-30 · updated 2026-06-17
• Weakness: CWE-190

Description

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 Linux: 9.0
• Klibc Project Klibc: before 2.0.9 — fixed in 2.0.9

How to fix

Upgrade to a fixed version: Klibc Project Klibc 2.0.9. Check the vendor advisory for mitigations.

References

• http://www.openwall.com/lists/oss-security/2021/04/30/1
• https://git.kernel.org/pub/scm/libs/klibc/klibc.git/commit/?id=292650f04c2b5348b4efbad61fb014ed09b4f3f2
• https://kernel.org/pub/linux/libs/klibc/2.0/
• https://lists.debian.org/debian-lts-announce/2021/06/msg00025.html
• https://lists.zytor.com/archives/klibc/2021-April/004593.html
• http://www.openwall.com/lists/oss-security/2021/04/30/1
• https://git.kernel.org/pub/scm/libs/klibc/klibc.git/commit/?id=292650f04c2b5348b4efbad61fb014ed09b4f3f2
• https://kernel.org/pub/linux/libs/klibc/2.0/
• https://lists.debian.org/debian-lts-announce/2021/06/msg00025.html
• https://lists.zytor.com/archives/klibc/2021-April/004593.html

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