CVE-2026-55973— NLnet Labs Unbound 输入验证错误漏洞

'dns-error-reporting: yes' leads to stack buffer overflow

In NLnet Labs Unbound 1.23.0 up to and including 1.25.1, when 'dns-error-reporting: yes' is set, the EDNS Report-Channel option (code 18) from the last upstream response is read and uses the option's length as the length of the agent domain. When a domain name check is performed on the agent domain, the returned lenght is not used and if the agent domain is followed by garbage, those bytes are moved onto the tail of the synthetic '_er.' report query name. That query name is later used in the iterator via a subquery to send out the DNS Error Report and when Unbound tries to walk that query name during 'find_closest_of_type()', it strips labels using the query name length rather than stopping at the embedded root, walks one byte past it, and feeds the first garbage byte to 'dname_query_hash()' as a label length writing over the stack variable 'labuf'. One ordinary upstream response from a delegated zone the attacker controls is sufficient to terminate the daemon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

输入验证不恰当

NLnet Labs Unbound 输入验证错误漏洞

NLnet Labs Unbound是荷兰NLnet Labs组织的域名系统解析服务器。 NLnet Labs Unbound 1.23.0版本至1.25.1版本存在输入验证错误漏洞，该漏洞源于当启用‘dns-error-reporting: yes’时，程序读取上游响应的EDNS Report-Channel选项（代码18）并用其长度作为代理域长度，在对代理域执行域名检查时未使用返回长度，导致若代理域后存在垃圾数据，这些字节被移至‘_er.’报告查询名称尾部，后续在‘find_closest_of_ty

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