CVE-2026-42534

描述

NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability in the jostle logic that could defeat its purpose and degrade resolution performance. Retransmits of the same query could renew the age of slow running queries and not allow the jostle logic to see them as aged and potential targets for replacement with new queries. An adversary who can query a vulnerable Unbound and who can control a domain name server that replies slowly and/or maliciously to Unbound's queries can exploit the vulnerability and degrade the resolution performance of Unbound. When Unbound's 'num-queries-per-thread' reaches its limit, the jostle logic kicks in. When a new query comes in, half of the available queries that are also slow to resolve are candidates for replacement. The vulnerability then happens because duplicate queries that need resolution would skew the aging result by using the timestamp of the latest duplicate query instead of the original one that started the resolution effort. Cache and local data response performance remains unaffected. Coordinated attacks could raise this to a denial of resolution service. Unbound 1.25.1 contains a patch with a fix to attach an initial, non-updatable start time for incoming queries that allow the jostle logic to work as intended.

如何修補 CVE-2026-42534

要修補 CVE-2026-42534,請將受影響套件升級到下列已修補版本。

• —升級至 1.25.1-r0 或更新版本
• —未列出修補版本

CVE-2026-42534 正在被利用嗎?

低 — EPSS 為 0.5%,目前沒有觀察到大規模利用活動。

受影響套件(2)

• from 0, < 1.25.1-r0
• from 0

CVSS 分數

參考連結(2)

• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2026-42534
• ADVISORYsecurity.alpinelinux.org/vuln/CVE-2026-42534