How severe is CVE-2021-31871?

CVE-2021-31871 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-31871 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (77th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-31871?

CVE-2021-31871 primarily affects Klibc Project Klibc. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-31871?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-31871 published?

CVE-2021-31871 was published on 2021-04-30 and last updated on 2026-06-17.

CVE-2021-31871

CVE-2021-31871 is a high-severity vulnerability in Klibc Project Klibc with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-190.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 2% (77th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-190
Affected product: Klibc Project Klibc
Published: 2021-04-30
Last modified: 2026-06-17

Description

An issue was discovered in klibc before 2.0.9. An integer overflow in the cpio command may result in a NULL pointer dereference on 64-bit systems.

Frequently asked questions

What is CVE-2021-31871?: An issue was discovered in klibc before 2.0.9. An integer overflow in the cpio command may result in a NULL pointer dereference on 64-bit systems.
How severe is CVE-2021-31871?: CVE-2021-31871 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-31871 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (77th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-31871?: CVE-2021-31871 primarily affects Klibc Project Klibc. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-31871?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-31871 published?: CVE-2021-31871 was published on 2021-04-30 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:klibc_project:klibc:*:*:*:*:*:*:x64:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

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