This Red Hat advisory addresses five vulnerabilities in dnsmasq, including multiple heap buffer overflows (CVE-2026-2291, CVSS 7.3 HIGH; CVE-2026-4892), an infinite loop (CVE-2026-4890, CVSS 7.5 HIGH), and a DNS validation bypass (CVE-2026-4893), which could lead to denial of service, information disclosure, or remote code execution. The update is rated Important and applies to Red Hat Enterprise Linux 9.6 Extended Update Support and related variants. Affected systems should be patched using the provided Red Hat update mechanism.
Red Hat Product Errata RHSA-2026:34508 - Security Advisory Issued: 2026-07-01 Updated: 2026-07-01 RHSA-2026:34508 - Security Advisory Overview Updated Packages Synopsis Important: dnsmasq security update Type/Severity Security Advisory: Important Red Hat Lightspeed patch analysis Identify and remediate systems affected by this advisory. View affected systems Topic An update for dnsmasq is now available for Red Hat Enterprise Linux 9.6 Extended Update Support. 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) 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 Update Support 9.6 x86_64 Red Hat Enterprise Linux Server - AUS 9.6 x86_64 Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 9.6 s390x Red Hat Enterprise Linux for Power, little endian - Extended Update Support 9.6 ppc64le Red Hat Enterprise Linux for ARM 64 - Extended Update Support 9.6 aarch64 Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions 9.6 ppc64le Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 9.6 x86_64 Red Hat Enterprise Linux for ARM 64 - 4 years of updates 9.6 aarch64 Red Hat Enterprise Linux for IBM z Systems - 4 years of updates 9.6 s390x Red Hat Enterprise Linux for x86_64 - Extended Life Cycle 9.6 x86_64 Red Hat Enterprise Linux for ARM 64 - Extended Life Cycle 9.6 aarch64 Red Hat Enterprise Linux for Power, little endian - Extended Life Cycle 9.6 ppc64le Red Hat Enterprise Linux for IBM z Systems - Extended Life Cycle 9.6 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 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 Note: More recent versions of these packages may be available. Click a package name for more details. Red Hat Enterprise Linux for x86_64 - Extended Update Support 9.6 SRPM dnsmasq-2.85-17.el9_6.1.src.rpm SHA-256: 3ad24239a776558aa5e3ed332c21891d235e062ebdc5a0ca34ca59adbdd8a606 x86_64 dnsmasq-2.85-17.el9_6.1.x86_64.rpm SHA-256: fc0574348898b7eae4a14129ef05370d23b0823bc434b77ac9a8e44b40b2796a dnsmasq-debuginfo-2.85-17.el9_6.1.x86_64.rpm SHA-256: 403eddd03fbd578191b2e843e17c7bb980f9b42f12eb8e93ea8dc1cba2d97bca dnsmasq-debugsource-2.85-17.el9_6.1.x86_64.rpm SHA-256: cd6a197d0a5bdd5faac125061262485e132bfc2897c2c99b3141d9508c12f204 dnsmasq-utils-2.85-17.el9_6.1.x86_64.rpm SHA-256: 2d8d33cfb600f6c4018d4e59618218e007fb23a205adfcb5ef3a23ba58a13068 dnsmasq-utils-debuginfo-2.85-17.el9_6.1.x86_64.rpm SHA-256: 663edf6ec59eaa645d115ebba7e5e8229bb65f03f5f140a1163e43dc9cf47996 Red Hat Enterprise Linux Server - AUS 9.6 SRPM dnsmasq-2.85-17.el9_6.1.src.rpm SHA-256: 3ad24239a776558aa5e3ed332c21891d235e062ebdc5a0ca34ca59adbdd8a606 x86_64 dnsmasq-2.85-17.el9_6.1.x86_64.rpm SHA-256: fc0574348898b7eae4a14129ef05370d23b0823bc434b77ac9a8e44b40b2796a dnsmasq-debuginfo-2.85-17.el9_6.1.x86_64.rpm SHA-256: 403eddd03fbd578191b2e843e17c7bb980f9b42f12eb8e93ea8dc1cba2d97bca dnsmasq-debugsource-2.85-17.el9_6.1.x86_64.rpm SHA-256: cd6a197d0a5bdd5faac125061262485e132bfc2897c2c99b3141d9508c12f204 dnsmasq-utils-2.85-17.el9_6.1.x86_64.rpm SHA-256: 2d8d33cfb600f6c4018d4e59618218e007fb23a205adfcb5ef3a23ba58a13068 dnsmasq-utils-debuginfo-2.85-17.el9_6.1.x86_64.rpm SHA-256: 663edf6ec59eaa645d115ebba7e5e8229bb65f03f5f140a1163e43dc9cf47996 Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 9.6 SRPM dnsmasq-2.85-17.el9_6.1.src.rpm SHA-256: 3ad24239a776558aa5e3ed332c21891d235e062ebdc5a0ca34ca59adbdd8a606 s390x dnsmasq-2.85-17.el9_6.1.s390x.rpm SHA-256: b1fe87b5f20673e42c1078224cd7b47021de15b4320a86d3cd5f0be75bc643f0 dnsmasq-debuginfo-2.85-17.el9_6.1.s390x.rpm SHA-256: 44fe92a038d96872f0896288b08b3dba77823a17e5968b39ed777a7d6b99f87a dnsmasq-debugsource-2.85-17.el9_6.1.s390x.rpm SHA-256: bfff712343053fef4886c523a9c93f8c9b0b32d7d58d89f5e1ae030f756b6993 dnsmasq-utils-2.85-17.el9_6.1.s390x.rpm SHA-256: 10cf034c8c1189de2c60f96632f5cec81f22ef324c38e81a33c678b14eaf2fe9 dnsmasq-utils-debuginfo-2.85-17.el9_6.1.s390x.rpm SHA-256: 99bef025a3f375b5f496d50b0da642337bf7841774adcb850d65554d427ac965 Red Hat Enterprise Linux for Power, little endian - Extended Update Support 9.6 SRPM dnsmasq-2.85-17.el9_6.1.src.rpm SHA-256: 3ad24239a776558aa5e3ed332c21891d235e062ebdc5a0ca34ca59adbdd8a606 ppc64le dnsmasq-2.85-17.el9_6.1.ppc64le.rpm SHA-256: eb13feec855ac75c2a4c5a906e2c4e0d56ceccd760bbab14b544cb137313391c dnsmasq-debuginfo-2.85-17.el9_6.1.ppc64le.rpm SHA-256: d5d55de31b101cd3e1a81bec57c6f17e13bf4fc84540c2d62c87727e99a57a18 dnsmasq-debugsource-2.85-17.el9_6.1.ppc64le.rpm SHA-256: c72d1138aa0b585f3b710b1b6feebba00a660d19b1b54f3e2d4fa0e3f4e4d8ed dnsmasq-utils-2.85-17.el9_6.1.ppc64le.rpm SHA-256: e3583d27c8eee9390480c2f2fcd8febbf58c0dd20daaeef6e4361e2cf940616c dnsmasq-utils-debuginfo-2.85-17.el9_6.1.ppc64le.rpm SHA-256: 6e1a631095073f7337e7ded918b44f2295fe9ae38ae1a90eafd587ff673d48ca Red Hat Enterprise Linux for ARM 64 - Extended Update Support 9.6 SRPM dnsmasq-2.85-17.el9_6.1.src.rpm SHA-256: 3ad24239a776558aa5e3ed332c21891d235e062ebdc5a0ca34ca59adbdd8a606 aarch64 dnsmasq-2.85-17.el9_6.1.aarch64.rpm SHA-256: 228f9db590e5ad51fd29a2ad3c9c1e38349842c3c76509df81a1c4421060bd46 dnsmasq-debuginfo-2.85-17.el9_6.1.aarch64.rpm SHA-256: e797a1e573f8b3fdf923e8e4e993b6d2b2ad87727234e9d2b14ec825e0365a89 dnsmasq-debugsource-2.85-17.el9_6.1.aarch64.rpm SHA-256: 3e863618639961addc8a50f7886b3937daf7657cf5e5f2cca49631139dcd175a dnsmasq-utils-2.85-17.el9_6.1.aarch64.rpm SHA-256: 6692c3dc4bad159ebd8615b6d23f0da52278bb1521285d9b1b5c22d930363e96 dnsmasq-utils-debuginfo-2.85-17.el9_6.1.aarch64.rpm SHA-256: c44779e3188231afe3e67435fe7cc8a073ca7b3e103a8732e0316309d3511160 Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions 9.6 SRPM dnsmasq-2.85-17.el9_6.1.src.rpm SHA-256: 3ad24239a776558aa5e3ed332c21891d235e062ebdc5a0ca34ca59adbdd8a606 ppc64le dnsmasq-2.85-17.el9_6.1.ppc64le.rpm SHA-256: eb13feec855ac75c2a4c5a906e2c4e0d56ceccd760bbab14b544cb137313391c dnsmasq-debuginfo-2.85-17.el9_6.1.ppc64le.rpm SHA-256: d5d55de31b101cd3e1a81bec57c6f17e13bf4fc84540c2d62c87727e99a57a18 dnsmasq-debugsource-2.85-17.el9_6.1.ppc64le.rpm SHA-256: c72d1138aa0b585f3b710b1b6feebba00a660d19b1b54f3e2d4fa0e3f4e4d8ed dnsmasq-utils-2.85-17.el9_6.1.ppc64le.rpm SHA-256: e3583d27c8eee9390480c2f2fcd8febbf58c0dd20daaeef6e4361e2cf940616c dnsmasq-utils-debuginfo-2.85-17.el9_6.1.ppc64le.rpm SHA-256: 6e1a631095073f7337e7ded918b44f2295fe9ae38ae1a90eafd587ff673d48ca Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 9.6 SRPM dnsmasq-2.85-17.el9_6.1.src.rpm SHA-256: 3ad24239a776558aa5e3ed332c21891d235e062ebdc5a0ca34ca59adbdd8a606 x86_64 dnsmasq-2.85-17.el9_6.1.x86_64.rpm SHA-256: fc0574348898b7eae4a14129ef05370d23b0823bc434b77ac9a8e44b40b2796a dnsmasq-debuginfo-2.85-17.el9_6.1.x86_64.rpm SHA-256: 403eddd03fbd578191b2e843e17c7bb980f9b42f12eb8e93ea8dc1cba2d97bca dnsmasq-debugsource-2.85-17.el9_6.1.x86_64.rpm SHA-256: cd6a197d0a5bdd5faac125061262485e132bfc2897c2c99b3141d9508c12f204 dnsmasq-utils-2.85-17.el9_6.1.x86_64.rpm SHA-256: 2d8d33cfb600f6c4018d4e59618218e007fb23a205adfcb5ef3a23ba58a13068 dnsmasq-utils-debuginfo-2.85-17.el9_6.1.x86_64.rpm SHA-256: 663edf6ec59eaa645d115ebba7e5e8229bb65f03f5f140a1163e43dc9cf47996 Red Hat Enterprise Linux for ARM 64 - 4 years of updates 9.6 SRPM dnsmasq-2.85-17.el9_6.1.src.rpm SHA-256: 3ad24239a776558aa5e3ed332c21891d235e062ebdc5a0ca34ca59adbdd8a606 aarch64 dnsmasq-2.85-17.el9_6.1.aarch64.rpm SHA-256: 228f9db590e5ad51fd29a2ad3c9c1e38349842c3c76509df81a1c4421060bd46 dnsmasq-debuginfo-2.85-17.el9_6.1.aarch64.rpm SHA-256: e797a1e573f8b3fdf923e8e4e993b6d2b2ad87727234e9d2b14ec825e0365a89 dnsmasq-debugsource-2.85-17.el9_6.1.aarch64.rpm SHA-256: 3e863618639961addc8a50f7886b3937daf7657cf5e5f2cca49631139dcd175a dnsmasq-utils-2.85-17.el9_6.1.aarch64.rpm SHA-256: 6692c3dc4bad159ebd8615b6d23f0da52278bb1521285d9b1b5c22d930363e96 dnsmasq-utils-debuginfo-2.85-17.el9_6.1.aarch64.rpm SHA-256: c44779e3188231afe3e67435fe7cc8a073ca7b3e103a8732e0316309d3511160 Red Hat Enterprise Linux for IBM z Systems - 4 years of updates 9.6 SRPM dnsmasq-2.85-17.el9_6.1.src.rpm SHA-256: 3ad24239a776558aa5e3ed332c21891d235e062ebdc5a0ca34ca59adbdd8a606 s390x dnsmasq-2.85-17.el9_6.1.s390x.rpm SHA-256: b1fe87b5f20673e42c1078224cd7b47021de15b4320a86d3cd5f0be75bc643f0 dnsmasq-debuginfo-2.85-17.el9_6.1.s390x.rpm SHA-256: 44fe92a038d96872f0896288b08b3dba77823a17e5968b39ed777a7d6b99f87a dnsmasq-debugsource-2.85-17.el9_6.1.s390x.rpm SHA-256: bfff712343053fef4886c523a9c9