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CVE-2026-42960— Possible cache poisoning via promiscuous records for the authority section

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 1.25.0及之前版本存在安全漏洞，该漏洞源于权威区段中混杂记录导致缓存投毒，可能允许攻击者通过伪造响应或分片攻击投毒缓存。

AI Predicted 7.5 Difficulty: Moderate EPSS 0.27% · P17

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 1

VendorProduct Version RangeStatus
NLnet Labs Unbound < 1.25.1 affected
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I. Basic Information for CVE-2026-42960

Vulnerability Information
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Vulnerability Title
Possible cache poisoning via promiscuous records for the authority section
Source: CVE Program / CVE List V5
Vulnerability Description
NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to poisoning via promiscuous records for the authority section. Promiscuous RRSets that complement DNS replies in the authority section can be used to trick Unbound to cache such records. If an adversary is able to attach such records in a reply (i.e., spoofed packet, fragmentation attack) he would be able to poison Unbound's cache. A malicious actor can exploit the possible poisonous effect by injecting RRSets other than NS that are also accompanied by address records in a reply, for example MX. This could be achieved by trying to spoof a reply packet or fragmentation attacks. Unbound would then accept the relative address records in the additional section and cache them if the authority RRSet has enough trust at this point, i.e., in-zone data for the delegation point. Unbound 1.25.1 contains a patch with a fix that disregards address records from the additional section if they are not explicitly relevant only to authority NS records, mitigating the possible poison effect. This is a complement fix to CVE-2025-11411.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:H/E:P/U:Amber
Source: CVE Program / CVE List V5
Vulnerability Type
在可信数据中接受外来的不可信数据
Source: CVE Program / CVE List V5
Vulnerability Title
NLnet Labs Unbound 安全漏洞
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 1.25.0及之前版本存在安全漏洞，该漏洞源于权威区段中混杂记录导致缓存投毒，可能允许攻击者通过伪造响应或分片攻击投毒缓存。
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 0 ~ 1.25.1 -

II. Public POCs for CVE-2026-42960

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III. Intelligence Information for CVE-2026-42960

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Vendor Advisories for CVE-2026-42960 (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-2026-42959 8.7 HIGH Crash during DNSSEC validation of malicious content
CVE-2026-42944 8.7 HIGH Heap overflow with multiple NSID, COOKIE, PADDING EDNS options
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-2026-42923 Degradation of service with unbounded NSEC3 hash calculations
CVE-2026-32792 Packet of death with DNSCrypt
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-349

V. Comments for CVE-2026-42960

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