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CVE-2026-32792— Packet of death with DNSCrypt

Quick assessment

Affected
NLnet Labs Unbound
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 Unbound是NLnet Labs开源的一个高性能DNS解析器。 NLnet Labs Unbound 1.6.2版本至1.25.0版本存在缓冲区错误漏洞，该漏洞源于DNSCrypt数据包读取过程下溢可能导致堆溢出。恶意攻击者可利用单个恶意DNSCrypt查询触发漏洞，其解密明文完全由0x00字节组成且不包含预期的0x80标记，导致Unbound读取超出必要字节。基于底层内存分配器和内存布局，可能导致堆溢出并引发崩溃。

AI Predicted 5.3 Difficulty: Hard EPSS 0.34% · P27

Possible ATT&CK Techniques 1 AI

T1498 · Network Denial of Service

Affected Version Matrix 1

VendorProduct Version RangeStatus
NLnet Labs Unbound 1.6.2< 1.25.1 affected
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I. Basic Information for CVE-2026-32792

Vulnerability Information
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Vulnerability Title
Packet of death with DNSCrypt
Source: CVE Program / CVE List V5
Vulnerability Description
NLnet Labs Unbound 1.6.2 up to and including version 1.25.0 has a denial of service vulnerability when compiled with DNSCrypt support ('--enable-dnscrypt'). A bad DNSCrypt query could underflow Unbound's DNSCrypt packet reading procedure that may lead to heap overflow. A malicious actor can exploit the vulnerability with a single bad DNSCrypt query that its decrypted plaintext consists entirely of '0x00' bytes and does not contain the expected '0x80' marker. Unbound would then start reading more bytes than necessary until it finds a non-'0x00' byte. Based on the underlying memory allocator and the memory layout, it could lead to heap overflow while reading followed by a crash. Likelihood of a crash is low, since it relies heavily on the underlying memory allocator and the memory layout. If the heap overflow does not happen, Unbound's later packet checks will deny the packet. Unbound 1.25.1 contains a patch with a fix to bound reading in the given buffer space.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
Source: CVE Program / CVE List V5
Vulnerability Type
缺失特殊元素净化处理不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
NLnet Labs Unbound 缓冲区错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
NLnet Labs Unbound是NLnet Labs开源的一个高性能DNS解析器。 NLnet Labs Unbound 1.6.2版本至1.25.0版本存在缓冲区错误漏洞，该漏洞源于DNSCrypt数据包读取过程下溢可能导致堆溢出。恶意攻击者可利用单个恶意DNSCrypt查询触发漏洞，其解密明文完全由0x00字节组成且不包含预期的0x80标记，导致Unbound读取超出必要字节。基于底层内存分配器和内存布局，可能导致堆溢出并引发崩溃。
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 Unbound 1.6.2 ~ 1.25.1 -

II. Public POCs for CVE-2026-32792

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III. Intelligence Information for CVE-2026-32792

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Other References for CVE-2026-32792 (1)

Same Patch Batch · NLnet Labs · 2026-05-20 · 11 CVEs total

CVE-2026-33278 9.1 CRITICAL Possible arbitrary code execution during DNSSEC validation
CVE-2026-42534 6.9 MEDIUM Jostle logic bypass degrades resolution performance
CVE-2026-44390 6.9 MEDIUM Unbounded name compression in certain cases causes degradation of service
CVE-2026-41292 6.6 MEDIUM Long list of incoming EDNS options degrades performance
CVE-2026-42959 Crash during DNSSEC validation of malicious content
CVE-2026-42923 Degradation of service with unbounded NSEC3 hash calculations
CVE-2026-42944 Heap overflow with multiple NSID, COOKIE, PADDING EDNS options
CVE-2026-42960 Possible cache poisoning via promiscuous records for the authority section
CVE-2026-40622 Another 'ghost domain names' attack variant
CVE-2026-44608 Use after free and crash under special conditions in RPZ code

IV. Related Vulnerabilities

Same product: Unbound
Same vendor: NLnet Labs
Same weakness: CWE-166

V. Comments for CVE-2026-32792

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