Out-of-bounds write in Unbound - CVE-2026-81642
Published: September 16, 2026 / Updated: September 19, 2026
Vulnerability identifier: #VU150193
CSH Severity: High
CVSS v4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-81642
CWE-ID: CWE-787
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to execute arbitrary code or cause a denial of service.
The vulnerability exists due to a buffer overflow in Unbound's DNSSEC validator when processing a DNSKEY with an owner compression pointer to its own RDATA. A remote attacker can control a malicious zone and query a vulnerable Unbound instance to execute arbitrary code or cause a denial of service.
Affected software
Unbound
Fedora
unbound
Fedora
unbound
How to mitigate CVE-2026-81642
Install security update from vendor's website.
Unbound - update to 1.26.1
unbound - addressed in versions 1.26.1-1.fc43, 1.26.1-1.fc44, 1.26.1-1.fc45
unbound - addressed in versions 1.26.1-1.fc43, 1.26.1-1.fc44, 1.26.1-1.fc45