Insufficient verification of data authenticity in Unbound - CVE-2026-50248
Published: July 23, 2026
Vulnerability identifier: #VU139217
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-50248
CWE-ID: CWE-345
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: NLnet Labs
Affected software:
Unbound
Unbound
Detailed vulnerability description
The vulnerability allows a remote attacker to replace the entire zone data or the resolver's entire response policy.
The vulnerability exists due to improper validation of configured primary hostnames in auth/rpz zone XFR endpoint selection when resolving a configured primary hostname to BOGUS A/AAAA records. A remote attacker can spoof the hostname's A/AAAA record to replace the entire zone data or the resolver's entire response policy.
No valid RRSIG is required for exploitation.
How to mitigate CVE-2026-50248
Install security update from vendor's website.