5.9 MEDIUM
- CVSS version (CVSS): 3.1
- Attack Vector (AV): Network (N)
- Attack Complexity (AC): High (H)
- Privileges Required (PR): None (N)
- User Interaction (UI): None (N)
- Scope (S): Unchanged (U)
- Confidentiality (C): None (N)
- Integrity (I): None (N)
- Availability (A): High (H)
- Modified Attack Vector (MAV): Network (N)
- Modified Attack Complexity (MAC): High (H)
- Modified Privileges Required (MPR): None (N)
- Modified User Interaction (MUI): None (N)
- Modified Confidentiality (MC): None (N)
- Modified Scope (MS): Unchanged (U)
- Modified Integrity (MI): None (N)
- Modified Availability (MA): High (H)
Activity log
- Created suggestion
Libunbound applications configured with 'unwanted-reply-threshold' could eventually be abruptly terminated
With NLnet Labs Unbound up to and including version 1.25.1, applications using libunbound and configured with 'unwanted-reply-threshold', could eventually be abruptly terminated if the threshold is reached and libunbound needs to call 'libworker_alloc_cleanup' since the function is absent from the function call allow list. When an application using libunbound sets 'unwanted-reply-threshold' to any non-zero value and the iterator queries an authoritative that replies with enough wrong-transaction-ID UDP datagrams to cross the threshold, the 'libworker_alloc_cleanup' will eventually be called. Since the function is absent from the function call allow list, this leads to a fatal exit of libunbound and eventual termination of the embedding application.Unbound itself is not affected since its relevant function 'worker_alloc_cleanup' is registed in the allow list and proceeds to perform the documented cache flush.
References
-
https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-44621.txt vendor-advisory
Affected products
- <1.25.2
Matching in nixpkgs
pkgs.unbound
Validating, recursive, and caching DNS resolver
pkgs.unbound-full
Validating, recursive, and caching DNS resolver
pkgs.unbound-with-systemd
Validating, recursive, and caching DNS resolver
pkgs.luaPackages.luaunbound
A binding to libunbound
pkgs.lua51Packages.luaunbound
A binding to libunbound
pkgs.lua52Packages.luaunbound
A binding to libunbound
pkgs.lua53Packages.luaunbound
A binding to libunbound
pkgs.lua54Packages.luaunbound
A binding to libunbound
pkgs.lua55Packages.luaunbound
A binding to libunbound
pkgs.luajitPackages.luaunbound
A binding to libunbound
pkgs.prometheus-unbound-exporter
Prometheus exporter for Unbound DNS resolver
pkgs.python313Packages.pyunbound
Python library for Unbound, the validating, recursive, and caching DNS resolver
pkgs.python314Packages.pyunbound
Python library for Unbound, the validating, recursive, and caching DNS resolver
pkgs.haskellPackages.unbound-generics
Support for programming with names and binders using GHC Generics
pkgs.haskellPackages.unbounded-delays
Unbounded thread delays and timeouts
pkgs.haskellPackages.unbound-kind-generics
Support for programming with names and binders using kind-generics
Package maintainers
-
@mweinelt Martin Weinelt <hexa@darmstadt.ccc.de>
-
@Scrumplex Sefa Eyeoglu <contact@scrumplex.net>