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CVE-2026-44608— Use after free and crash under special conditions in RPZ code

AI Predicted 5.3 Difficulty: Moderate EPSS 0.04% · P12

Possible ATT&CK Techniques 1AI

T1496 · Resource Hijacking

Affected Version Matrix 1

VendorProductVersion RangeStatus
NLnet LabsUnbound1.14.0< 1.25.1affected
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I. Basic Information for CVE-2026-44608

Vulnerability Information
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Vulnerability Title
Use after free and crash under special conditions in RPZ code
Source: NVD (National Vulnerability Database)
Vulnerability Description
NLnet Labs Unbound 1.14.0 up to and including version 1.25.0 has a locking inconsistency vulnerability that when certain conditions are met (multi-threaded, RPZ XFR reload, RPZ zone with 'rpz-nsip'/'rpz-nsdname' triggers) it could result in heap use-after-free and eventual crash. An adversary can exploit the vulnerability if conditions are first met on a vulnerable Unbound, i.e., multi-threaded, an RPZ zone with 'rpz-nsip'/'rpz-nsdname' triggers and an ongoing XFR for that RPZ zone. Local RPZ files do not trigger the vulnerability. If the timing is right and an XFR happens at the same time another thread needs to read that RPZ zone, the reader may not hold the lock long enough and the thread applying the XFR may free objects that the reader is about to walk causing the use-after-free. Unbound 1.25.1 contains a patch with a fix to the locking code.
Source: NVD (National Vulnerability Database)
CVSS Information
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Type
资源加锁不恰当
Source: NVD (National Vulnerability Database)
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 1.14.0至1.25.0版本存在安全漏洞，该漏洞源于锁定不一致，在特定条件下可能导致堆释放后重用和崩溃。
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

VendorProductAffected VersionsCPESubscribe
NLnet LabsUnbound 1.14.0 ~ 1.25.1 -

II. Public POCs for CVE-2026-44608

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III. Intelligence Information for CVE-2026-44608

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Other References for CVE-2026-44608 (1)

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

CVE-2026-41292Long list of incoming EDNS options degrades performance
CVE-2026-42959Crash during DNSSEC validation of malicious content
CVE-2026-42923Degradation of service with unbounded NSEC3 hash calculations
CVE-2026-42944Heap overflow with multiple NSID, COOKIE, PADDING EDNS options
CVE-2026-42960Possible cache poisoning via promiscuous records for the authority section
CVE-2026-42534Jostle logic bypass degrades resolution performance
CVE-2026-32792Packet of death with DNSCrypt
CVE-2026-40622Another 'ghost domain names' attack variant
CVE-2026-44390Unbounded name compression in certain cases causes degradation of service
CVE-2026-33278Possible arbitrary code execution during DNSSEC validation

IV. Related Vulnerabilities

Same product: Unbound
Same vendor: NLnet Labs
Same weakness: CWE-413

V. Comments for CVE-2026-44608

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