CVEvulnerability

CVE-2026-32792

4.6 MEDIUM Published 2026-05-20 Modified 2026-07-24 Official page ↗
Status
Analyzed
Published
2026-05-20
Last modified
2026-07-24
Assigner
[email protected]
CVSS 4.0 ([email protected])
4.6 MEDIUM — CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Green
CVSS 3.1 ([email protected])
5.3 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Weaknesses
CWE-125, CWE-166

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.

Affected configurations

• nlnetlabs unbound (>= 1.6.2 < 1.25.1)

Related

Weakness · CWE (2)

  • CWE-125 Out-of-bounds Read weakness
  • CWE-166 Improper Handling of Missing Special Element weakness

References