In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, a single client query for a deeply nested name under a DNSSEC-signed parent can cause… (CVE-2026-50045)
Description
NLnet Labs Unbound versions 1.22.0 through 1.25.1 contain a vulnerability where a single client query for a deeply nested name under a DNSSEC-signed parent causes Unbound to send more upstream packets than the configured 'max-global-quota'. This bypasses the intended limit on upstream amplification traffic. The vulnerability has a CVSS score of 5.3 (medium severity) and does not impact confidentiality or integrity but affects availability. No known exploits are reported in the wild. The affected versions include multiple specific builds primarily on Ubuntu platforms.
CVSS v3.1
Score 5.3medium
Affected software
pkg:deb/ubuntu/unbound?arch=source&distro=esm-infra-legacy/trustypkg:deb/ubuntu/unbound?arch=source&distro=esm-infra-legacy/xenialpkg:deb/ubuntu/unbound?arch=source&distro=esm-infra/bionicpkg:deb/ubuntu/unbound?arch=source&distro=esm-infra/focalpkg:deb/ubuntu/unbound?arch=source&distro=jammypkg:deb/ubuntu/unbound?arch=source&distro=noblepkg:deb/ubuntu/unbound?arch=source&distro=stonkingpkg:deb/ubuntu/unbound?arch=source&distro=resoluteRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
In NLnet Labs Unbound versions 1.22.0 up to and including 1.25.1, a vulnerability exists where a single client query for a deeply nested DNS name under a DNSSEC-signed parent causes Unbound to exceed the configured 'max-global-quota' for upstream packets. This effectively bypasses the security configuration intended to limit upstream amplification traffic, potentially leading to resource exhaustion or denial of service conditions. The vulnerability is identified as CVE-2026-50045 with a CVSS v3.1 base score of 5.3, reflecting a medium severity impact primarily on availability.
Potential Impact
The vulnerability allows an attacker to bypass the configured limit on upstream amplification traffic by causing Unbound to send more packets upstream than allowed. This can lead to increased resource consumption and potential denial of service conditions. There is no impact on confidentiality or integrity. No known exploits are currently reported in the wild.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, consider monitoring for unusual upstream traffic patterns related to deeply nested DNS queries under DNSSEC-signed parents and apply any recommended vendor mitigations once published.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- UBUNTU-CVE-2026-50045
- Osv Schema Version
- 1.7.0
- Ecosystems
- ["Ubuntu:Pro:14.04:LTS","Ubuntu:Pro:16.04:LTS","Ubuntu:Pro:18.04:LTS","Ubuntu:Pro:20.04:LTS","Ubuntu:22.04:LTS","Ubuntu:24.04:LTS","Ubuntu:26.10","Ubuntu:26.04:LTS"]
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6ad3f6142cdf04f656664159
Added to database: 10/17/2026, 22:26:28 UTC
Last enriched: 10/18/2026, 01:01:58 UTC
Last updated: 10/18/2026, 01:01:58 UTC
Views: 2
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