How severe is CVE-2026-4437?

CVE-2026-4437 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-2026-4437 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (21st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-4437?

CVE-2026-4437 affects Gnu Glibc. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-4437?

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.

Does CVE-2026-4437 have an EU (EUVD) identifier?

Yes. CVE-2026-4437 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-13796.

When was CVE-2026-4437 published?

CVE-2026-4437 was published on 2026-03-20 and last updated on 2026-06-17.

CVE-2026-4437

CVE-2026-4437 is a high-severity vulnerability in Gnu Glibc 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-125.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 0% (21st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-13796
Weakness: CWE-125
Affected product: Gnu Glibc
Published: 2026-03-20
Last modified: 2026-06-17

Description

Calling gethostbyaddr or gethostbyaddr_r with a configured nsswitch.conf that specifies the library's DNS backend in the GNU C Library version 2.34 to version 2.43 could, with a crafted response from the configured DNS server, result in a violation of the DNS specification that causes the application to treat a non-answer section of the DNS response as a valid answer.

Frequently asked questions

What is CVE-2026-4437?: Calling gethostbyaddr or gethostbyaddr_r with a configured nsswitch.conf that specifies the library's DNS backend in the GNU C Library version 2.34 to version 2.43 could, with a crafted response from the configured DNS server, result in a violation of the DNS specification that causes the application to treat a non-answer section of the DNS response as a valid answer.
How severe is CVE-2026-4437?: CVE-2026-4437 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-2026-4437 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (21st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-4437?: CVE-2026-4437 affects Gnu Glibc. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-4437?: 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.
Does CVE-2026-4437 have an EU (EUVD) identifier?: Yes. CVE-2026-4437 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-13796.
When was CVE-2026-4437 published?: CVE-2026-4437 was published on 2026-03-20 and last updated on 2026-06-17.

References

https://sourceware.org/bugzilla/show_bug.cgi?id=34014

Affected products (1)

cpe:2.3:a:gnu:glibc:*:*:*:*:*:*:*:*

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