Is CVE-2021-3998 in the CISA KEV catalog?

No. CVE-2021-3998 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-3998?

CVE-2021-3998 has a CVSS v3 base score of 7.5 (HIGH).

What is the EPSS score for CVE-2021-3998?

CVE-2021-3998 has an EPSS score of 1.44% (70th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-3998?

Upgrade glibc on debian 12 to 2.33-4 or later. Fixes are available for 3 affected products.

CVE & CISA-KEV Catalog

CVE-2021-3998

HIGHEPSS 70th pctl

7.5

CVSS v3

NVD

Description

A flaw was found in glibc. The realpath() function can mistakenly return an unexpected value, potentially leading to information leakage and disclosure of sensitive data.

CWE-125Out-of-bounds Read CWE-252

How to fix

Remediation Available

glibcDebian

Fixed in:2.33-4CVE-2021-3998

glibcUbuntu

Fixed in:2.27-3ubuntu1.5USN-5310-1

Fixed in:2.31-0ubuntu9.7USN-5310-1

libc6Ubuntu

Fixed in:2.27-3ubuntu1.5USN-5310-1

Fixed in:2.31-0ubuntu9.7USN-5310-1

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityNone

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Exploit Intelligence

1.44%probability of exploitation in 30 days

70thpercentile

Elevated risk: more likely to be exploited than 70% of all known CVEs.

References

Patch3

Third-Party Advisory3

Other references2

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-06-09.