CVE-2026-81642 — unbound
CRITICALCVE-2026-81642 is a critical-severity (CVSS 9.8) CWE-122 vulnerability. A fix is available — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-81642.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-81642 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,987 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Description
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.
Affected Products
unboundnlnetlabsDetection & mitigation playbook
VulnerabilityDetect
Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).
Fix
Upgrade the affected component to the fixed release for CVE-2026-81642, or apply your distribution's backported patch — distro builds are often patched at an older version number, so check your vendor's advisory rather than the upstream version alone.
Workarounds
Constrain what reaches the vulnerable code: limit the size and shape of untrusted input, isolate the affected component in a sandboxed or least-privileged process, and enable the platform's memory-safety mitigations (ASLR, stack protector, hardened allocator) so an out-of-bounds access is more likely to fail closed than to be exploitable.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.Source: Red Hat security advisory for CVE-2026-81642 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 10 | unbound-0:1.24.2-7.el10_2.6 | RHSA-2026:71419 |
| Red Hat Enterprise Linux 10.0 Extended Update Support | unbound-0:1.20.0-18.el10_0.13 | RHSA-2026:71459 |
| Red Hat Enterprise Linux 7 Extended Lifecycle Support | unbound-0:1.6.6-5.el7_9.2 | RHSA-2026:72199 |
| Red Hat Enterprise Linux 8 | unbound-0:1.16.2-5.14.el8_10.4 | RHSA-2026:70754 |
| Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support | unbound-0:1.7.3-15.el8_4.4 | RHSA-2026:72183 |
| Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support | unbound-0:1.7.3-17.el8_6.8 | RHSA-2026:72110 |
| Red Hat Enterprise Linux 8.8 Telecommunications Update Service | unbound-0:1.16.2-5.el8_8.6 | RHSA-2026:72264 |
| Red Hat Enterprise Linux 9 | unbound-0:1.24.2-3.el9_8.8 | RHSA-2026:71487 |
Frequently Asked Questions
Is CVE-2026-81642 in your dependencies?
Find it across , including transitive dependencies.