Heap-based buffer overflow in Unbound - CVE-2026-32792
Published: May 20, 2026
Vulnerability identifier: #VU131985
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-32792
CWE-ID: CWE-122
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 cause a denial of service.
The vulnerability exists due to a heap-based buffer overflow in Unbound's DNSCrypt packet reading procedure when processing a crafted DNSCrypt query. A remote attacker can send a specially crafted DNSCrypt query to cause a denial of service.
Only installations compiled with DNSCrypt support are vulnerable. The crafted query's decrypted plaintext consists entirely of 0x00 bytes and lacks the expected 0x80 marker. A crash depends on the underlying memory allocator and memory layout.
How to mitigate CVE-2026-32792
Install security update from vendor's website.