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CVE-2026-18916— Remote TCP DoS by throttling the TCP receive window

Quick assessment

Affected
NLnet Labs NSD
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

NLnet Labs NSD是荷兰NLnet Labs组织的一款DNS服务器软件。 NLnet Labs NSD 3.2.11版本至4.15.1之前版本存在数字错误漏洞，该漏洞源于TCP查询后限制TCP接收窗口导致整数下溢，可能导致远程客户端崩溃NSD服务子进程，持续崩溃可导致拒绝所有TCP服务。

CVSS 6.9 · Medium EPSS 0.28% · P19

Affected Version Matrix 1

VendorProduct Version RangeStatus
NLnet Labs NSD 3.2.11< 4.15.1 affected
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I. Basic Information for CVE-2026-18916

Vulnerability Information
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Vulnerability Title
Remote TCP DoS by throttling the TCP receive window
Source: CVE Program / CVE List V5
Vulnerability Description
Any remote client can crash a NSD serve child, by throttling the TCP receive window after a TCP query. By continuously crashing the serve childs, the remote client can denial all TCP service to this NSD instance.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
整数下溢(超界折返)
Source: CVE Program / CVE List V5
Vulnerability Title
NLnet Labs NSD 数字错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
NLnet Labs NSD是荷兰NLnet Labs组织的一款DNS服务器软件。 NLnet Labs NSD 3.2.11版本至4.15.1之前版本存在数字错误漏洞，该漏洞源于TCP查询后限制TCP接收窗口导致整数下溢，可能导致远程客户端崩溃NSD服务子进程，持续崩溃可导致拒绝所有TCP服务。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
NLnet Labs NSD 3.2.11 ~ 4.15.1 -

II. Public POCs for CVE-2026-18916

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III. Intelligence Information for CVE-2026-18916

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Other References for CVE-2026-18916 (1)

Same Patch Batch · NLnet Labs · 2026-08-26 · 4 CVEs total

CVE-2026-18664 8.2 HIGH Wrong interpretation of ACL ranges
CVE-2026-19401 8.2 HIGH Remote UDP DoS by sending multiple DNS Cookie options
CVE-2026-19538 8.2 HIGH Bypass of BLOCKED ACL items on proxy protocol port over TCP or TLS

IV. Related Vulnerabilities

Same product: NSD
Same vendor: NLnet Labs
Same weakness: CWE-191

V. Comments for CVE-2026-18916

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