How severe is CVE-2026-4438?

CVE-2026-4438 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2026-4438 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (9th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-4438?

CVE-2026-4438 affects Gnu Glibc. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-4438?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-4438 have an EU (EUVD) identifier?

Yes. CVE-2026-4438 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-13798.

When was CVE-2026-4438 published?

CVE-2026-4438 was published on 2026-03-20 and last updated on 2026-06-17.

CVE-2026-4438

CVE-2026-4438 is a medium-severity vulnerability in Gnu Glibc with a CVSS 3.x base score of 5.4. 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-20.

Key facts

Severity: Medium (CVSS 3.x base score 5.4)
EPSS exploit prediction: 0% (9th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-13798
Weakness: CWE-20
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 result in an invalid DNS hostname being returned to the caller in violation of the DNS specification.

Frequently asked questions

What is CVE-2026-4438?: 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 result in an invalid DNS hostname being returned to the caller in violation of the DNS specification.
How severe is CVE-2026-4438?: CVE-2026-4438 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-4438 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (9th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-4438?: CVE-2026-4438 affects Gnu Glibc. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-4438?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-4438 have an EU (EUVD) identifier?: Yes. CVE-2026-4438 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-13798.
When was CVE-2026-4438 published?: CVE-2026-4438 was published on 2026-03-20 and last updated on 2026-06-17.

References

https://sourceware.org/bugzilla/show_bug.cgi?id=34015

Affected products (1)

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

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