CVE-2026-92694— FastNetMon: IPv6 host counters map iterated without lock, racing concurrent inserts

Quick assessment

Affected

pavel-odintsov fastnetmon

Exploitation

No confirmed in-the-wild exploitation; assess based on exposure

Recommended action

Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

FastNetMon 是一款高性能的 DDoS 检测器与传感器。在 1.2.9 及更早版本中，FastNetMon 在文件的函数中，负责绘制 IPv6 主要流量来源（top-talkers）的屏幕渲染线程，在遍历时未持有互斥锁；与此同时，函数会向该映射插入新键，并可能触发对该映射的重新哈希操作。该竞态条件要求中包含目标 IPv6 地址段。此问题在负载下会导致已确认的未定义行为；虽然理论上可能引发进程崩溃，但实际测试中并未观察到崩溃，因此尚未证实存在可靠的服务拒绝（DoS）攻击。截至本次评估，尚未发布包含

CVSS 5.9 · Medium Updated Nov 06, 2026

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

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Vulnerability Information

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Vulnerability Title

FastNetMon: IPv6 host counters map iterated without lock, racing concurrent inserts

Source: CVE Program / CVE List V5

Vulnerability Description

FastNetMon is a high-performance DDoS detector and sensor. In version 1.2.9 and earlier, FastNetMon's IPv6 top-talkers screen-draw thread in draw_table_ipv6() in src/fastnetmon_logic.cpp iterates ipv6_host_counters.average_speed_map without holding counter_map_mutex while recalculate_speed() inserts new keys and may rehash the same map. The race requires networks_list to include the targeted IPv6 range. It causes confirmed undefined behavior under load; a process crash is plausible but was not observed, so reliable denial of service has not been established. No fixed release is available as of this review.

Source: 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:H

Source: CVE Program / CVE List V5

Vulnerability Type

使用共享资源的并发执行不恰当同步问题(竞争条件)

Source: CVE Program / CVE List V5

Affected Products

Vendor	Product	Affected Versions	CPE	Subscribe
pavel-odintsov	fastnetmon	<= 1.2.9	-

II. Public POCs for CVE-2026-92694

#	POC Description	Source Link	Shenlong Link

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III. Intelligence Information for CVE-2026-92694

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Other References for CVE-2026-92694 (3)

https://github.com/pavel-odintsov/fastnetmon/pull/1087 x_refsource_MISC
https://github.com/pavel-odintsov/fastnetmon/security/advisories/GHSA-phrw-2q76-5m7h x_refsource_CONFIRM
https://github.com/pavel-odintsov/fastnetmon/commit/1294724ea931dc78fe545360f2193398bba35381 x_refsource_MISC

https://www.cve.org/CVERecord?id=CVE-2026-92694

Same Patch Batch · pavel-odintsov · 2026-11-05 · 6 CVEs total

CVE-2026-92698	8.2 HIGH	FastNetMon: sFlow header_size field trusted as parser capture length causes remote out-of-
CVE-2026-92695	8.2 HIGH	FastNetMon: Legacy pcap parse_packet() has no bounds checking, causing out-of-bounds read
CVE-2026-92693	8.2 HIGH	FastNetMon: IPv6 Fragment header dereferenced without bounds check in shared packet parser
CVE-2026-92697	7.5 HIGH	FastNetMon: NetFlow v9 unbounded strlen() on interface-description field causes remote out
CVE-2026-93424	7.5 HIGH	FastNetMon: NetFlow/IPFIX template cache returns unlocked pointers, causing heap-use-after

IV. Related Vulnerabilities

Same product: fastnetmon

Same vendor: pavel-odintsov

Same weakness: CWE-362