CVE-2026-18916: CWE-191: Integer Underflow in NLnet Labs NSD
Description
CVE-2026-18916 is an integer underflow vulnerability in NLnet Labs NSD version 3.2.11. A remote attacker can cause a denial of service by crashing NSD server child processes through throttling the TCP receive window after a TCP query. This continuous crashing results in denial of all TCP services from the affected NSD instance.
CVSS v4.0
Score 6.9medium
Affected software
NLnet Labs
NSD
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability involves an integer underflow (CWE-191) in NLnet Labs NSD 3.2.11. An unauthenticated remote client can manipulate the TCP receive window after sending a TCP query, causing the NSD server child process to crash repeatedly. This leads to a denial of service by preventing the NSD instance from handling TCP requests.
Potential Impact
An attacker can remotely cause a denial of service by repeatedly crashing NSD server child processes, resulting in unavailability of TCP services on the affected NSD instance. There is no indication of privilege escalation, data disclosure, or code execution from the provided data.
Mitigation Recommendations
No official patch or remediation is currently available. Users should monitor the vendor advisory for updates. Until a fix is released, consider limiting exposure of NSD TCP services to untrusted networks or applying network-level protections to mitigate potential denial of service attempts.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- NLnet Labs
- Date Reserved
- 2026-08-05T07:36:55.457Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6a8ea959acd9273b499fef52
Added to database: 08/26/2026, 08:52:41 UTC
Last enriched: 09/10/2026, 11:39:40 UTC
Last updated: 10/10/2026, 18:48:17 UTC
Views: 71
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