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.

The remote RockyLinux 9 host has packages installed that are affected by multiple vulnerabilities as referenced in the RLSA-2026:20597 advisory.

    * glibc: glibc: Incorrect DNS response parsing via crafted DNS server response (CVE-2026-4437)

    * glibc: glibc: Invalid DNS hostname returned via gethostbyaddr functions (CVE-2026-4438)

    * glibc: glibc: Denial of Service via iconv() function with specific character sets (CVE-2026-4046)

Tenable has extracted the preceding description block directly from the RockyLinux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote RockyLinux 10 host has packages installed that are affected by multiple vulnerabilities as referenced in the RLSA-2026:19061 advisory.

    * glibc: glibc: Incorrect DNS response parsing via crafted DNS server response (CVE-2026-4437)

    * glibc: glibc: Invalid DNS hostname returned via gethostbyaddr functions (CVE-2026-4438)

Tenable has extracted the preceding description block directly from the RockyLinux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote MiracleLinux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the AXSA:2026-726:04 advisory.

    * glibc: glibc: Denial of Service via iconv() function with specific character sets (CVE-2026-4046)

Tenable has extracted the preceding description block directly from the MiracleLinux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Redhat Enterprise Linux 9 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2026:20597 advisory.

    The glibc packages provide the standard C libraries (libc), POSIX thread libraries (libpthread), standard     math libraries (libm), and the name service cache daemon (nscd) used by multiple programs on the system.
    Without these libraries, the Linux system cannot function correctly.

    Security Fix(es):

    * glibc: glibc: Incorrect DNS response parsing via crafted DNS server response (CVE-2026-4437)

    * glibc: glibc: Invalid DNS hostname returned via gethostbyaddr functions (CVE-2026-4438)

    * glibc: glibc: Denial of Service via iconv() function with specific character sets (CVE-2026-4046)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Redhat Enterprise Linux 10 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2026:19061 advisory.

    The glibc packages provide the standard C libraries (libc), POSIX thread libraries (libpthread), standard     math libraries (libm), and the name service cache daemon (nscd) used by multiple programs on the system.
    Without these libraries, the Linux system cannot function correctly.

    Security Fix(es):

    * glibc: glibc: Incorrect DNS response parsing via crafted DNS server response (CVE-2026-4437)

    * glibc: glibc: Invalid DNS hostname returned via gethostbyaddr functions (CVE-2026-4438)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote SUSE Linux SLED15 / SLED_SAP15 / SLES15 / SLES_SAP15 / openSUSE 15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2026:1369-1 advisory.

    - CVE-2026-4437: incorrect DNS response parsing via crafted DNS server response (bsc#1260078).
    - CVE-2026-4438: invalid DNS hostname returned via gethostbyaddr functions (bsc#1260082).

Tenable has extracted the preceding description block directly from the SUSE security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

An update of the glibc package has been released.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - 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. (CVE-2026-4437)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Severity
318034	RockyLinux 9 : glibc (RLSA-2026:20597)	Nessus	Rocky Linux Local Security Checks	medium
317963	RockyLinux 10 : glibc (RLSA-2026:19061)	Nessus	Rocky Linux Local Security Checks	medium
317384	MiracleLinux 8 : glibc-2.28-251.el8_10.37 (AXSA:2026-726:04)	Nessus	Miracle Linux Local Security Checks	medium
316898	RHEL 9 : glibc (RHSA-2026:20597)	Nessus	Red Hat Local Security Checks	medium
315399	RHEL 10 : glibc (RHSA-2026:19061)	Nessus	Red Hat Local Security Checks	medium
306682	SUSE SLED15 / SLES15 / openSUSE 15 Security Update : glibc (SUSE-SU-2026:1369-1)	Nessus	SuSE Local Security Checks	medium
305122	Photon OS 5.0: Glibc PHSA-2026-5.0-0802	Nessus	PhotonOS Local Security Checks	medium
303238	Linux Distros Unpatched Vulnerability : CVE-2026-4437	Nessus	Misc.	high

Detections

Analytics

CVE-2026-4437

high

Tenable Plugins

medium

medium

medium

medium

medium

medium

medium

high