CVE-2026-44390— NLnet Labs Unbound 安全漏洞

Unbounded name compression in certain cases causes degradation of service

NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability when handling replies with very large RRsets that Unbound needs to perform name compression for. Malicious upstream responses with very large RRsets with records that don't share a suffix above the root can cause Unbound to spend a considerable time applying name compression to downstream replies. This can lead to degraded performance and eventually denial of service in well orchestrated attacks. An adversary can exploit the vulnerability by querying Unbound for the specially crafted contents of a malicious zone with very large RRsets. Before Unbound replies to the query it will try to apply name compression which was an unbounded operation that could lock the CPU until the whole packet was complete. A compression limit was introduced in 1.21.1 for this but it didn't account for the case where records would not share any suffix above the root. That causes Unbound to go in a different code path because of the compression tree lookup failure and eventually not increment the compression counter for those operations. Unbound 1.25.1 contains a patch with a fix that increments the compression counter regardless of the compression tree lookup. This is a complement fix to CVE-2024-8508.

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算法复杂性

NLnet Labs Unbound 安全漏洞

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，该漏洞源于处理大型RRset时名称压缩操作未绑定，可能导致性能下降和拒绝服务。

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