CVE-2026-50252— NLnet Labs Unbound 信任管理问题漏洞
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。
NLnet Labs Unbound是荷兰NLnet Labs组织的域名系统解析服务器。 NLnet Labs Unbound 1.4.22版本至1.25.1版本存在信任管理问题漏洞，该漏洞源于UDP源端口随机化机制在启用SO_REUSEPORT负载均衡策略时可被利用，允许恶意行为者获取端口与工作线程的映射关系，从而降低每个线程的随机端口数量，容易受到DNS缓存中毒攻击。
影响版本矩阵 1
| 厂商 | 产品 | 版本范围 | 状态 |
|---|---|---|---|
| NLnet Labs | Unbound | 1.4.22< 1.25.2 |
affected |
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一、 漏洞 CVE-2026-50252 基础信息
漏洞信息
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Vulnerability Title
Possible cache poisoning attack by mapping source port population per thread
来源: CVE Program / CVE List V5
Vulnerability Description
In NLnet Labs Unbound 1.4.22 up to and including 1.25.1, UDP source port is randomized and intended to serve as a secret value that increases the entropy of DNS transactions. When resolver load balancing policies depend on the source port while their outcome is revealed this secrecy is undermined. The vulnerability arises when the load balancing policy is consistent with respect to the incoming source UDP port and IP address while heavily depending on the incoming source UDP port as a randomization source. When the SO_REUSEPORT configuration option is enabled ('so-reuseport: yes') in Unbound (by default), it meets these conditions, making it vulnerable for DNS cache poisoning attacks. Upon startup, Unbound randomly partitions the available UDP source port space into disjoint subsets of (almost) equal size, assigning each subset to a specific worker thread. When an incoming DNS query is received, the kernel’s SO_REUSEPORT load balancing mechanism deterministically assigns the query to a socket associated with a particular thread. All outgoing DNS queries generated during the resolution of that request use source ports selected exclusively from the port subset assigned to the corresponding thread. Since these port subsets are disjoint across threads, the source port observed in a resolver’s outgoing query to an authoritative name server serves as a reliable indicator of the worker thread that processed the original client query. A malicious actor can acquire the mapping between incoming UDP source ports (for a given fixed source IP address) and Unbound worker threads and leverage it to conduct DNS cache poisoning attacks by effectively lowering the random port population per thread.
来源: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:H/E:P/U:Amber
来源: CVE Program / CVE List V5
Vulnerability Type
在可信数据中接受外来的不可信数据
来源: CVE Program / CVE List V5
Vulnerability Title
NLnet Labs Unbound 信任管理问题漏洞
来源: 中国国家信息安全漏洞库 CNNVD
Vulnerability Description
NLnet Labs Unbound是荷兰NLnet Labs组织的域名系统解析服务器。 NLnet Labs Unbound 1.4.22版本至1.25.1版本存在信任管理问题漏洞，该漏洞源于UDP源端口随机化机制在启用SO_REUSEPORT负载均衡策略时可被利用，允许恶意行为者获取端口与工作线程的映射关系，从而降低每个线程的随机端口数量，容易受到DNS缓存中毒攻击。
来源: 中国国家信息安全漏洞库 CNNVD
CVSS Information
N/A
来源: 中国国家信息安全漏洞库 CNNVD
Vulnerability Type
N/A
来源: 中国国家信息安全漏洞库 CNNVD
受影响产品
| 厂商 | 产品 | 影响版本 | CPE | 订阅 |
|---|---|---|---|---|
| NLnet Labs | Unbound | 1.4.22 ~ 1.25.2 | - |
|
二、漏洞 CVE-2026-50252 的公开POC
| # | POC 描述 | 源链接 | 神龙链接 |
|---|
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CVE-2026-50252 其他参考 (1)
同批安全公告 · NLnet Labs · 2026-07-22 · 共 24 条
| CVE-2026-55973 | 7.5 HIGH | NLnet Labs Unbound 输入验证错误漏洞 |
| CVE-2026-32665 | 7.5 HIGH | NLnet Labs Unbound 输入验证错误漏洞 |
| CVE-2026-40691 | 7.5 HIGH | NLnet Labs Unbound 缓冲区错误漏洞 |
| CVE-2026-44690 | 7.5 HIGH | NLnet Labs Unbound 输入验证错误漏洞 |
| CVE-2026-50248 | 6.5 MEDIUM | NLnet Labs Unbound 输入验证错误漏洞 |
| CVE-2026-52863 | 5.9 MEDIUM | NLnet Labs Unbound 资源管理错误漏洞 |
| CVE-2026-55717 | 5.9 MEDIUM | NLnet Labs Unbound 异常处理不当漏洞 |
| CVE-2026-55991 | 5.9 MEDIUM | NLnet Labs Unbound 数字错误漏洞 |
| CVE-2026-50046 | 5.9 MEDIUM | NLnet Labs Unbound 资源管理错误漏洞 |
| CVE-2026-14586 | 5.9 MEDIUM | NLnet Labs Unbound 异常处理不当漏洞 |
| CVE-2026-56444 | 5.9 MEDIUM | NLnet Labs Unbound 资源管理错误漏洞 |
| CVE-2026-55990 | 5.9 MEDIUM | NLnet Labs Unbound 异常处理不当漏洞 |
| CVE-2026-44621 | 5.9 MEDIUM | NLnet Labs Unbound 异常处理不当漏洞 |
| CVE-2026-50251 | 5.3 MEDIUM | NLnet Labs Unbound 输入验证错误漏洞 |
| CVE-2026-50045 | 5.3 MEDIUM | NLnet Labs Unbound 资源管理错误漏洞 |
| CVE-2026-56416 | 4.8 MEDIUM | NLnet Labs Unbound 加密问题漏洞 |
| CVE-2026-46582 | 3.7 LOW | NLnet Labs Unbound 处理逻辑错误漏洞 |
| CVE-2026-44687 | 3.7 LOW | NLnet Labs Unbound 数字错误漏洞 |
| CVE-2026-41637 | 3.7 LOW | NLnet Labs Unbound 资源管理错误漏洞 |
| CVE-2026-54478 | 3.7 LOW | NLnet Labs Unbound 授权问题漏洞 |
显示前 20 条，共 24 条。 查看全部 → →
IV. Related Vulnerabilities
V. Comments for CVE-2026-50252
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