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CVE-2026-97206— DNS-over-QUIC (DoQ) path-migration can lead to use-after-free on multi-threaded deployments.

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 开发的 Unbound DNS 解析器（版本 1.22.0 至 1.26.1，含两端）存在一个 DNS-over-QUIC（DoQ）生命周期缺陷。该漏洞在多线程运行模式下，可被远程 DoQ 客户端利用。当客户端触发 QUIC 路径迁移时，系统可能进入流/连接清理流程，而此时网格（mesh）回复仍持有指向该 DoQ 流的指针。清理过程会释放该 DoQ 流，随后当待处理的网格回复完成时，会解引用一个已失效的指针，从而导致程序崩溃。

CVSS 7.5 · High

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-97206

Vulnerability Information
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Vulnerability Title
DNS-over-QUIC (DoQ) path-migration can lead to use-after-free on multi-threaded deployments.
Source: CVE Program / CVE List V5
Vulnerability Description
NLnet Labs Unbound, 1.22.0 up to and including version 1.26.1, contains a DNS-over-QUIC (DoQ) lifetime bug reachable by a remote DoQ client under multi-threaded operation. A client-triggered QUIC path migration can enter stream/connection cleanup while a mesh reply still retains a pointer to the DoQ stream. Cleanup frees the DoQ stream and when the pending mesh reply later completes it dereferences a stale pointer leading to a crash.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
释放后使用
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
NLnet Labs Unbound 1.22.0 ~ 1.26.2 -

II. Public POCs for CVE-2026-97206

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III. Intelligence Information for CVE-2026-97206

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Other References for CVE-2026-97206 (1)

Same Patch Batch · NLnet Labs · 2026-10-21 · 5 CVEs total

CVE-2026-50106 6.5 MEDIUM Possible insecure NXDOMAIN for non-existing records under a configured island trust anchor
CVE-2026-109125 5.3 MEDIUM Possible cache poisoning vulnerability via a cache side-channel exposed by 'unwanted-reply
CVE-2026-96405 5.3 MEDIUM Aggregate DNS name chained pointer decompression work leads to degradation of service.
CVE-2026-35501 3.7 LOW Bypass of a configured island trust anchor underneath an insecure parent from an atacker-c

IV. Related Vulnerabilities

Same product: Unbound
Same vendor: NLnet Labs
Same weakness: CWE-416

V. Comments for CVE-2026-97206

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