RHSA-2026:96241 - Security Advisory

Topic

An update for dnsmasq is now available for Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support and Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On.

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)

Bug Fix(es) and Enhancement(s):

• dnsmasq: New DNSSEC trust anchor key 2024 (JIRA:RHEL-272333)

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 - Extended Life Cycle Long Life 8.6 x86_64
• Red Hat Enterprise Linux Server - AUS 8.6 x86_64

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

CVEs

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

References

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