CVE-2026-41637

Published: Lug 22, 2026 Last Modified: Lug 24, 2026
ExploitDB:
Other exploit source:
Google Dorks:
LOW 3,7
Source: [email protected]
Attack Vector: network
Attack Complexity: high
Privileges Required: none
User Interaction: none
Scope: unchanged
Confidentiality: none
Integrity: none
Availability: low

Description

AI Translation Available

In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, client terminated DNS-over-QUIC (DoQ) queries are not accounted properly by Unbound resulting in low-cost inflation of the waiting number of replies for already in-flight resolution queries. This results in degradation of resolution service for new clients for already in-flight queries. A malicious actor can exploit the vulnerability by issuing DoQ queries for query names that need resolution and proceeding on immediately terminating the query by one of STOP_SENDING/RESET_STREAM/CONNECTION_CLOSE QUIC frames. Those terminated DoQ queries are not properly counted for and keep inflating the number of waiting replies for in-flight queries. When the maximum is reached, it results in silent query drops for new clients needing resolution for already in-flight queries. This vulnerability needs Unbound to be compiled with DoQ support ('--with-libngtcp2') and the 'quic-port' to be configured for the listening interfaces. Additionally, a malicious actor needs access to multiple source IPs to bypass the by-default configured 'wait-limit' option.

772

Missing Release of Resource after Effective Lifetime

Draft
Abstraction: Base Structure: Simple
Common Consequences
Security Scopes Affected:
Availability
Potential Impacts:
Dos: Resource Consumption (Other) Dos: Resource Consumption (Memory) Dos: Resource Consumption (Cpu)
Applicable Platforms
Technologies: Mobile
Likelihood of Exploit: High
View CWE Details
Application

Unbound by Nlnetlabs

Product Information
Vendor Nlnetlabs
Product Unbound
Version Range Affected
From 1.22.0 (inclusive)
To 1.25.2 (exclusive)
cpe:2.3:a:nlnetlabs:unbound:*:*:*:*:*:*:*:*
Common Platform Enumeration - Standardized vulnerability identification
https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-41637.t…
https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-41637.txt