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Fencer Intel
critical 9.8

CVE-2026-81642 json

Heap buffer overflow and possible Remote Code Execution when digesting DNSKEY

published last mo. modified last mo. also EUVD-2026-80291

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.0%
EPSS 1.0% chance of exploitation in 30 days, percentile 62%
public exploits
0
none known

Summary

In NLnet Labs Unbound up to and including 1.26.0, a vulnerability was found in the DNSSEC validator that enables denial of service and possible remote code execution as a result of digesting DNSKEYs. A DNSKEY with an owner compression pointer to its own RDATA can overflow the digest buffer. Remote code execution is possible through attacker controlled data. An adversary can exploit the vulnerability by controlling a malicious zone and querying a vulnerable Unbound.

Patch / fix

  • NLnet Labs Unbound 1.26.1
  • unbound Debian 13 1.26.1-0+deb13u1
  • unbound Debian 14 1.26.1-1

debian advisories DEBIAN-CVE-2026-81642

  • unbound Ubuntu 22.04 LTS 1.13.1-1ubuntu5.16
  • unbound Ubuntu 24.04 LTS 1.19.2-1ubuntu3.10
  • unbound Ubuntu 26.04 LTS 1.24.2-1ubuntu2.3
  • unbound Ubuntu Pro 14.04 LTS 1.4.22-1ubuntu4.14.04.3+esm4
  • unbound Ubuntu Pro 16.04 LTS 1.5.8-1ubuntu1.1+esm4
  • unbound Ubuntu Pro 18.04 LTS 1.6.7-1ubuntu2.6+esm5
  • unbound Ubuntu Pro 20.04 LTS 1.9.4-2ubuntu1.11+esm2

ubuntu advisories UBUNTU-CVE-2026-81642

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • unbound RHEL 9 1.24.2-3.el9_8.8
  • unbound-libs RHEL 9 1.24.2-3.el9_8.8
  • unbound-dracut RHEL 9 1.24.2-3.el9_8.8
  • python3-unbound RHEL 9 1.24.2-3.el9_8.8
  • unbound RHEL 10.2 1.24.2-7.el10_2.6
  • unbound-libs RHEL 10.2 1.24.2-7.el10_2.6
  • unbound-utils RHEL 10.2 1.24.2-7.el10_2.6
  • unbound-anchor RHEL 10.2 1.24.2-7.el10_2.6

red hat advisories RHSA-2026:72264RHSA-2026:72199RHSA-2026:72183RHSA-2026:72110RHSA-2026:71611RHSA-2026:71610

  • unbound Linux Micro 6.1 1.26.1-slfo.1.1_1.1
  • unbound SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +6 more 1.26.1-150100.10.31.1
  • unbound SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Package Hub 15 SP7 +1 more 1.26.1-150600.23.24.1
  • unbound SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 1.26.1-160000.1.1
  • unbound Linux Micro 6.0 1.26.1-159998.1.1

suse advisories SUSE-SU-2026:24376-1SUSE-SU-2026:4624-1SUSE-SU-2026:4620-1SUSE-SU-2026:24128-1SUSE-SU-2026:24226-1SUSE-SU-2026:24135-1

  • unbound openSUSE Leap 16.0 1.26.1-160000.1.1
  • unbound openSUSE Tumbleweed 1.26.1-1.1

opensuse advisories openSUSE-SU-2026:22082-1openSUSE-SU-2026:11930-1

  • unbound AlmaLinux 10 1.24.2-7.el10_2.6
  • unbound-libs AlmaLinux 10 1.24.2-7.el10_2.6
  • unbound-utils AlmaLinux 10 1.24.2-7.el10_2.6
  • unbound-anchor AlmaLinux 10 1.24.2-7.el10_2.6
  • unbound-dracut AlmaLinux 10 1.24.2-7.el10_2.6
  • python3-unbound AlmaLinux 10 1.24.2-7.el10_2.6
  • unbound AlmaLinux 9 1.24.2-3.el9_8.8
  • unbound-libs AlmaLinux 9 1.24.2-3.el9_8.8

almalinux advisories ALSA-2026:71419ALSA-2026:71487ALSA-2026:70754

  • unbound Rocky Linux 9 1.24.2-3.el9_8.8
  • unbound Rocky Linux 10 1.24.2-7.el10_2.6
  • unbound Rocky Linux 8 1.16.2-5.14.el8_10.4

rocky linux advisories RLSA-2026:71487RLSA-2026:71419RLSA-2026:70754

  • unbound Alpine 3.23, Alpine 3.22 1.25.2-r0
  • unbound Alpine 3.24 1.25.2-r2

alpine advisories ALPINE-CVE-2026-81642

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • unbound Azure Linux 3.0 1.26.1-1

azure linux advisories AZL-101709

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Is CVE-2026-81642 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-81642 updated cvss 9.8

unbound: Unbound: Heap buffer overflow and possible Remote Code Execution when digesting DNSKEY

  • Red Hat Enterprise Linux 6 unbound, unbound-libs, unbound-python
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 8) unbound 1.16.2-5.14.el8_10.4, unbound-libs 1.16.2-5.14.el8_10.4, python3-unbound 1.16.2-5.14.el8_10.4
    fixed: vendor fix RHSA-2026:70754
  • Red Hat Enterprise Linux AppStream (v. 9) unbound 1.24.2-3.el9_8.8, unbound-libs 1.24.2-3.el9_8.8, unbound-dracut 1.24.2-3.el9_8.8, python3-unbound 1.24.2-3.el9_8.8
    fixed: vendor fix RHSA-2026:71487
  • Red Hat Enterprise Linux AppStream (v. 10) unbound 1.24.2-7.el10_2.6, unbound-libs 1.24.2-7.el10_2.6, unbound-utils 1.24.2-7.el10_2.6, unbound-anchor 1.24.2-7.el10_2.6, unbound-dracut 1.24.2-7.el10_2.6, python3-unbound 1.24.2-7.el10_2.6
    fixed: vendor fix RHSA-2026:71419
  • Red Hat Enterprise Linux AppStream AUS (v.8.4) unbound 1.7.3-15.el8_4.4, unbound-libs 1.7.3-15.el8_4.4
    fixed: vendor fix RHSA-2026:72183
  • Red Hat Enterprise Linux AppStream AUS (v.8.6) unbound 1.7.3-17.el8_6.8, unbound-libs 1.7.3-17.el8_6.8
    fixed: vendor fix RHSA-2026:72110
  • Red Hat Enterprise Linux AppStream E4S (v.8.8) unbound 1.16.2-5.el8_8.6, unbound-libs 1.16.2-5.el8_8.6, python3-unbound 1.16.2-5.el8_8.6
    fixed: vendor fix RHSA-2026:72264
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) unbound 1.16.2-3.el9_2.6, unbound-libs 1.16.2-3.el9_2.6, python3-unbound 1.16.2-3.el9_2.6
    fixed: vendor fix RHSA-2026:71610
show 12 more
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) unbound 1.16.2-8.el9_4.3, unbound-libs 1.16.2-8.el9_4.3, python3-unbound 1.16.2-8.el9_4.3
    fixed: vendor fix RHSA-2026:71611
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) unbound 1.20.0-18.el10_0.13, unbound-libs 1.20.0-18.el10_0.13
    fixed: vendor fix RHSA-2026:71459
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) unbound 1.16.2-19.el9_6.2, unbound-libs 1.16.2-19.el9_6.2
    fixed: vendor fix RHSA-2026:71460
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) unbound 1.7.3-15.el8_4.4, unbound-libs 1.7.3-15.el8_4.4
    fixed: vendor fix RHSA-2026:72183
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) unbound 1.7.3-17.el8_6.8, unbound-libs 1.7.3-17.el8_6.8
    fixed: vendor fix RHSA-2026:72110
  • Red Hat Enterprise Linux AppStream TUS (v.8.8) unbound 1.16.2-5.el8_8.6, unbound-libs 1.16.2-5.el8_8.6, python3-unbound 1.16.2-5.el8_8.6
    fixed: vendor fix RHSA-2026:72264
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) unbound-devel 1.24.2-3.el9_8.8, unbound-debuginfo 1.24.2-3.el9_8.8, unbound-debugsource 1.24.2-3.el9_8.8, unbound-libs-debuginfo 1.24.2-3.el9_8.8, python3-unbound-debuginfo 1.24.2-3.el9_8.8
    fixed: vendor fix RHSA-2026:71487
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) unbound-devel 1.24.2-7.el10_2.6, unbound-debuginfo 1.24.2-7.el10_2.6, unbound-debugsource 1.24.2-7.el10_2.6, unbound-libs-debuginfo 1.24.2-7.el10_2.6, unbound-utils-debuginfo 1.24.2-7.el10_2.6, unbound-anchor-debuginfo 1.24.2-7.el10_2.6, +1 more
    fixed: vendor fix RHSA-2026:71419
  • Red Hat Enterprise Linux Server (v. 7 ELS) unbound 1.6.6-5.el7_9.2, unbound-libs 1.6.6-5.el7_9.2 Red Hat Enterprise Linux Server Optional (v. 7 ELS) unbound-python 1.6.6-5.el7_9.2
    fixed: vendor fix RHSA-2026:72199
  • Red Hat Hardened Images unbound 1.26.1-1.hum1, unbound-libs 1.26.1-1.hum1, unbound-munin 1.26.1-1.hum1, unbound-utils 1.26.1-1.hum1, unbound-anchor 1.26.1-1.hum1, unbound-dracut 1.26.1-1.hum1, +1 more
    fixed: vendor fix RHSA-2026:68590
  • Red Hat CodeReady Linux Builder EUS (v.9.6) unbound-devel 1.16.2-19.el9_6.2, unbound-debuginfo 1.16.2-19.el9_6.2, unbound-debugsource 1.16.2-19.el9_6.2, unbound-libs-debuginfo 1.16.2-19.el9_6.2, python3-unbound-debuginfo 1.16.2-19.el9_6.2 Red Hat Enterprise Linux AppStream AUS (v.8.4) python3-unbound 1.7.3-15.el8_4.4 Red Hat Enterprise Linux AppStream AUS (v.8.6) python3-unbound 1.7.3-17.el8_6.8 Red Hat Enterprise Linux AppStream EUS (v. 10.0) unbound-anchor 1.20.0-18.el10_0.13, unbound-dracut 1.20.0-18.el10_0.13, python3-unbound 1.20.0-18.el10_0.13 Red Hat Enterprise Linux AppStream EUS (v.9.6) unbound-dracut 1.16.2-19.el9_6.2, python3-unbound 1.16.2-19.el9_6.2 Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) python3-unbound 1.7.3-15.el8_4.4
    +2 more products
    Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) python3-unbound 1.7.3-17.el8_6.8 Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) unbound-devel 1.20.0-18.el10_0.13, unbound-debuginfo 1.20.0-18.el10_0.13, unbound-debugsource 1.20.0-18.el10_0.13, unbound-libs-debuginfo 1.20.0-18.el10_0.13, unbound-utils-debuginfo 1.20.0-18.el10_0.13, unbound-anchor-debuginfo 1.20.0-18.el10_0.13, +1 more
    not affected: vulnerable code not present
  • Red Hat OpenShift Container Platform 4 unbound Red Hat OpenShift Container Platform 5 unbound
    not affected: vulnerable code not in execute path

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
total
Assessed
last mo.

Exploit prediction

0.96% chance of exploitation in the next 30 days, higher than 62% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 4.0 9.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:U/U:Red
CNA 4.0 9.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Red
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • NLnet Labs Unbound

Classification

Weakness
  • CWE-122 Heap-based Buffer Overflow

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.