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CVE-2026-12244— Heap overflow and crash with crafted SVCB RR

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 4.14.0版本至4.14.3之前版本存在安全漏洞，该漏洞源于在处理特制SVCB RR时，uint16_t变量在分配空间时发生整数溢出（总大小大于65535），导致堆溢出，攻击者可执行最多65509字节的受控头部写入。

AI Predicted 9.8 Difficulty: Easy EPSS 0.49% · P40

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 1

VendorProduct Version RangeStatus
NLnet Labs NSD 4.14.0< 4.14.3 affected
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I. Basic Information for CVE-2026-12244

Vulnerability Information
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Vulnerability Title
Heap overflow and crash with crafted SVCB RR
Source: CVE Program / CVE List V5
Vulnerability Description
If NSD is configured as secondary for a zone, the primary of that zone can crash NSD with an AXFR containing a DNS message with a special crafted SVCB RR with an rdata size of 65512, that let's an (uint16_t) variable that is used to allocate space needed for the RR wrap (because total size > 65535), causing a heap overflow. The attacker can perform a controlled (RCE class) head write of up to 65509 bytes
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
整数溢出或超界折返
Source: CVE Program / CVE List V5
Vulnerability Title
NLnet Labs NSD 缓冲区错误漏洞
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 4.14.0版本至4.14.3之前版本存在安全漏洞，该漏洞源于在处理特制SVCB RR时，uint16_t变量在分配空间时发生整数溢出（总大小大于65535），导致堆溢出，攻击者可执行最多65509字节的受控头部写入。
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 4.14.0 ~ 4.14.3 -

II. Public POCs for CVE-2026-12244

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III. Intelligence Information for CVE-2026-12244

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Vendor Advisories for CVE-2026-12244 (1)

Same Patch Batch · NLnet Labs · 2026-06-25 · 4 CVEs total

CVE-2026-12245 Denial of DNS over TLS service by any DoT client
CVE-2026-12246 Out of bounds stack write with crafted APL RR
CVE-2026-12490 Bypass of client certificate verification with transfer over TLS

IV. Related Vulnerabilities

Same product: NSD
Same vendor: NLnet Labs
Same weakness: CWE-190

V. Comments for CVE-2026-12244

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