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Unbound can be crashed by crafted DNS queries

published 24 days ago

Summary

The Red Hat Unbound DNS server and its Python bindings are vulnerable to specially crafted queries that could crash the service. This could interrupt name resolution for users and applications. Apply the latest Red Hat security update for the unbound packages to prevent the issue.

What to do

Update redhat python3-unbound to version 0:1.16.2-8.el9_4.3.
Update redhat python3-unbound-debuginfo to version 0:1.16.2-8.el9_4.3.
Update redhat unbound to version 0:1.16.2-8.el9_4.3.
Update redhat unbound-debuginfo to version 0:1.16.2-8.el9_4.3.
Update redhat unbound-debugsource to version 0:1.16.2-8.el9_4.3.
Update redhat unbound-libs to version 0:1.16.2-8.el9_4.3.
Update redhat unbound-libs-debuginfo to version 0:1.16.2-8.el9_4.3.

Affected software

Ecosystem	Vendor	Product	Affected versions
Red Hat:rhel_e4s:9.4::appstream	redhat	python3-unbound	< 0:1.16.2-8.el9_4.3 Fix: upgrade to 0:1.16.2-8.el9_4.3
Red Hat:rhel_e4s:9.4::appstream	redhat	python3-unbound-debuginfo	< 0:1.16.2-8.el9_4.3 Fix: upgrade to 0:1.16.2-8.el9_4.3
Red Hat:rhel_e4s:9.4::appstream	redhat	unbound	< 0:1.16.2-8.el9_4.3 Fix: upgrade to 0:1.16.2-8.el9_4.3
Red Hat:rhel_e4s:9.4::appstream	redhat	unbound-debuginfo	< 0:1.16.2-8.el9_4.3 Fix: upgrade to 0:1.16.2-8.el9_4.3
Red Hat:rhel_e4s:9.4::appstream	redhat	unbound-debugsource	< 0:1.16.2-8.el9_4.3 Fix: upgrade to 0:1.16.2-8.el9_4.3
Red Hat:rhel_e4s:9.4::appstream	redhat	unbound-libs	< 0:1.16.2-8.el9_4.3 Fix: upgrade to 0:1.16.2-8.el9_4.3
Red Hat:rhel_e4s:9.4::appstream	redhat	unbound-libs-debuginfo	< 0:1.16.2-8.el9_4.3 Fix: upgrade to 0:1.16.2-8.el9_4.3

Original advisory text

Red Hat Security Advisory: unbound security update

References

https://access.redhat.com/errata/RHSA-2026:71611 Vendor Advisory
https://access.redhat.com/security/updates/classification/#critical Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2535059 Third Party Advisory
https://security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_71611.... Vendor Advisory
https://access.redhat.com/security/cve/CVE-2026-81642 Third Party Advisory
https://www.cve.org/CVERecord?id=CVE-2026-81642 Vendor Advisory
https://nvd.nist.gov/vuln/detail/CVE-2026-81642 Vendor Advisory
https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-81642.txt Third Party Advisory

Fix within

Internet-facing 3 days

Internal 60 days

Not known to be exploited
Can be exploited automatically (estimated)
Gives an attacker full control (estimated)

Severity

9.8 Critical

Timeline

Published25 Sep 2026

Updated25 Sep 2026

First seen25 Sep 2026

Sources

RHSA-2026:71611 · OSV

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