CVE-2026-77860— Unbound serve-expired 绕过 wait-limit 漏洞
一分钟漏洞结论
影响对象
NLnet Labs Unbound
利用判断
尚无明确在野利用证据，仍需结合暴露面评估
建议动作
优先检查厂商安全公告和参考链接中的修复版本；无法立即升级时，限制受影响服务暴露并加强监测。
In NLnetLabs Unbound 1.20.0 up to and including 1.26.0, a vulnerability on the 'serve-expired' code path can cause a double decrement on the 'wait-limit' counter per client IP essentially bypassing one of the counter measures that was introduced for DNSBomb (C
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一、 漏洞 CVE-2026-77860 基础信息
漏洞信息
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Vulnerability Title
'serve-expired' can bypass Unbound 'wait-limit'
来源: CVE Program / CVE List V5
Vulnerability Description
In NLnetLabs Unbound 1.20.0 up to and including 1.26.0, a vulnerability on the 'serve-expired' code path can cause a double decrement on the 'wait-limit' counter per client IP essentially bypassing one of the counter measures that was introduced for DNSBomb (CVE-2024-33655). A malicious actor can exploit this by controlling an authoritative zone with short TTL, so cached entries expire quickly. Each 'slow' query, one the attacker's authoritative never answers, is followed by one query for an expired cached name, which is answered immediately via the 'serve-expired' path and decrements the counter twice. This second query was named 'pump'. By alternating slow queries and pumps, the attacker keeps the per-client counter at or below the configured 'wait-limit' indefinitely, and can hold an arbitrary number of pending queries from a single source IP, up to the global mesh quota (num-queries-per-thread); eventually bypassing one of the counter measures introduced for DNSBomb (CVE-2024-33655). This vulnerability is present on the 'serve-expired' code path.
来源: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
来源: CVE Program / CVE List V5
Vulnerability Type
对资源的重复操作
来源: CVE Program / CVE List V5
受影响产品
| 厂商 | 产品 | 影响版本 | CPE | 订阅 |
|---|---|---|---|---|
| NLnet Labs | Unbound | 1.20.0 ~ 1.26.1 | - |
|
二、漏洞 CVE-2026-77860 的公开POC
| # | POC 描述 | 源链接 | 神龙链接 |
|---|
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CVE-2026-77860 其他参考 (1)
-
https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-77860.txt vendor-advisory
同批安全公告 · NLnet Labs · 2026-09-16 · 共 9 条
| CVE-2026-81642 | 9.1 CRITICAL | DNSKEY 摘要堆缓冲区溢出导致远程代码执行漏洞 |
| CVE-2026-82717 | 8.4 HIGH | CNAME合成导致堆内存损坏漏洞 |
| CVE-2026-81634 | 7.5 HIGH | DNSSEC规范化过程中堆缓冲区溢出漏洞 |
| CVE-2026-78227 | 6.5 MEDIUM | DoQ 流重置重传中的释放后使用漏洞 |
| CVE-2026-82720 | 5.9 MEDIUM | DoH 流清理代码路径使用后再释放漏洞 |
| CVE-2026-85501 | 5.3 MEDIUM | DNSSEC算法复杂度攻击漏洞 |
| CVE-2026-80225 | 5.3 MEDIUM | TCP/DoT 持续查询导致服务性能下降 |
| CVE-2026-77955 | 4.4 MEDIUM | ZONEMD验证绕过窗口 |
IV. Related Vulnerabilities
V. Comments for CVE-2026-77860
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