CVE-2026-93011 PUBLISHED

Dnsmasq: dnsmasq: heap out-of-bounds write in dnssec validator via to_wire/from_wire transforms

Assigner: redhat
Reserved: 17.09.2026 Published: 29.10.2026 Updated: 29.10.2026

A flaw was found in dnsmasq. After a reduction of internal domain-name buffer sizes, the DNSSEC validator can write a few bytes past a name buffer when converting names to and from DNS wire format. An attacker who can cause the server to validate a crafted DNSSEC response may overwrite a small amount of adjacent heap metadata. DNSSEC support is not compiled in by default and must also be enabled at runtime.

Metrics

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
CVSS Score: 5.3

Product Status

Vendor Red Hat
Product Red Hat Ceph Storage 9
Versions Default: affected
Vendor Red Hat
Product Red Hat Enterprise Linux 10
Versions Default: affected
Vendor Red Hat
Product Red Hat Enterprise Linux 6
Versions Default: affected
Vendor Red Hat
Product Red Hat Enterprise Linux 7
Versions Default: affected
Vendor Red Hat
Product Red Hat Enterprise Linux 8
Versions Default: affected
Vendor Red Hat
Product Red Hat Enterprise Linux 9
Versions Default: affected
Vendor Red Hat
Product Red Hat OpenShift Container Platform 4
Versions Default: affected
Vendor Red Hat
Product Red Hat OpenShift Container Platform 4
Versions Default: affected
Vendor Red Hat
Product Red Hat OpenShift Container Platform 4
Versions Default: affected
Vendor Red Hat
Product Red Hat OpenShift Container Platform 4
Versions Default: affected
Vendor Red Hat
Product Red Hat OpenStack Platform 13 (Queens)
Versions Default: affected
Vendor Red Hat
Product Red Hat OpenStack Platform 18.0
Versions Default: affected

Workarounds

The following measures reduce risk:

  1. Do not enable --dnssec or --trust-anchor unless DNSSEC validation is required.
  2. Omit -DHAVE_DNSSEC from COPTS (this is the default build).
  3. If DNSSEC validation is required, restrict dnsmasq to trusted upstream resolvers.

Credits

  • Red Hat would like to thank Shubham Raj (Causal Security) for reporting this issue.

References

Problem Types

  • Out-of-bounds Write CWE