VULNERABILITY INTELLIGENCE

CVE-2026-32792

CVSS score5.3 MEDIUM
EPSS probability0.34%
CISA KEVNot currently listed
Published2026-05-20
Last modified2026-07-24
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Description

NLnet Labs Unbound 1.6.2 up to and including version 1.25.0 has a denial of service vulnerability when compiled with DNSCrypt support ('--enable-dnscrypt'). A bad DNSCrypt query could underflow Unbound's DNSCrypt packet reading procedure that may lead to heap overflow. A malicious actor can exploit the vulnerability with a single bad DNSCrypt query that its decrypted plaintext consists entirely of '0x00' bytes and does not contain the expected '0x80' marker. Unbound would then start reading more bytes than necessary until it finds a non-'0x00' byte. Based on the underlying memory allocator and the memory layout, it could lead to heap overflow while reading followed by a crash. Likelihood of a crash is low, since it relies heavily on the underlying memory allocator and the memory layout. If the heap overflow does not happen, Unbound's later packet checks will deny the packet. Unbound 1.25.1 contains a patch with a fix to bound reading in the given buffer space.

Weakness classification

  • sep@nlnetlabs.nl: CWE-125

Primary references