RHSA-2026:19158 - Security Advisory

Topic

An update for dnsmasq is now available for Red Hat Enterprise Linux 10.

Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

Description

The dnsmasq packages contain Dnsmasq, a lightweight DNS (Domain Name Server) forwarder and DHCP (Dynamic Host Configuration Protocol) server.

Security Fix(es):

• dnsmasq: dnsmasq: heap buffer overflow in cache via NAME_ESCAPE expansion (CVE-2026-2291)
• dnsmasq: NSEC bitmap parsing infinite loop (CVE-2026-4890)
• dnsmasq: RRSIG rdlen underflow leading to heap OOB read (CVE-2026-4891)
• dnsmasq: DHCPv6 CLID buffer overflow in helper process (CVE-2026-4892)
• dnsmasq: Broken ECS source validation bypass (CVE-2026-4893)
• dnsmasq: extract_addresses() OOB read via malformed rdlen (CVE-2026-5172)

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.

Solution

For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

Affected Products

• Red Hat Enterprise Linux for x86_64 10 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 10.2 x86_64
• Red Hat Enterprise Linux for IBM z Systems 10 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 10.2 s390x
• Red Hat Enterprise Linux for Power, little endian 10 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 10.2 ppc64le
• Red Hat Enterprise Linux for ARM 64 10 aarch64
• Red Hat Enterprise Linux for ARM 64 - Extended Update Support 10.2 aarch64
• Red Hat Enterprise Linux for ARM 64 - 4 years of updates 10.2 aarch64
• Red Hat Enterprise Linux for IBM z Systems - 4 years of updates 10.2 s390x
• Red Hat Enterprise Linux for Power, little endian - 4 years of support 10.2 ppc64le
• Red Hat Enterprise Linux for x86_64 - 4 years of updates 10.2 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Life Cycle 10.2 x86_64
• Red Hat Enterprise Linux for ARM 64 - Extended Life Cycle 10.2 aarch64
• Red Hat Enterprise Linux for Power, little endian - Extended Life Cycle 10.2 ppc64le
• Red Hat Enterprise Linux for IBM z Systems - Extended Life Cycle 10.2 s390x

Fixes

• BZ - 2439088 - CVE-2026-2291 dnsmasq: dnsmasq: heap buffer overflow in cache via NAME_ESCAPE expansion
• BZ - 2458516 - CVE-2026-4890 dnsmasq: NSEC bitmap parsing infinite loop
• BZ - 2458517 - CVE-2026-4891 dnsmasq: RRSIG rdlen underflow leading to heap OOB read
• BZ - 2458518 - CVE-2026-4892 dnsmasq: DHCPv6 CLID buffer overflow in helper process
• BZ - 2458519 - CVE-2026-4893 dnsmasq: Broken ECS source validation bypass
• BZ - 2458521 - CVE-2026-5172 dnsmasq: extract_addresses() OOB read via malformed rdlen

CVEs

• CVE-2026-2291
• CVE-2026-4890
• CVE-2026-4891
• CVE-2026-4892
• CVE-2026-4893
• CVE-2026-5172

References

• https://access.redhat.com/security/updates/classification/#important