CVE-2026-4890

Summary

A Denial of Service (DoS) vulnerability in the DNSSEC validation of dnsmasq allows remote attackers to cause a denial of service via a crafted DNS packet.

Affected Software

Weaknesses

• CWE-835: Loop with Unreachable Termination

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: yes
  • Technical Impact: partial

dnsmasq: NSEC bitmap parsing infinite loop

Additional References

• https://access.redhat.com/security/cve/CVE-2026-4890
• https://bugzilla.redhat.com/show_bug.cgi?id=2458516
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4890.json
• https://access.redhat.com/errata/RHSA-2026:19158
• https://access.redhat.com/errata/RHSA-2026:20589
• https://access.redhat.com/errata/RHSA-2026:34508
• https://access.redhat.com/errata/RHSA-2026:19373

References

• https://www.kb.cert.org/vuls/id/471747
• https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2026q2/018471.html
• https://thekelleys.org.uk/dnsmasq/CVE/
• https://github.com/NixOS/nixpkgs/pull/519093
• https://github.com/NixOS/nixpkgs/pull/519082
• https://github.com/pi-hole/FTL/releases/tag/v6.6.2

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