Bug 2567966 (CVE-2026-92694)

Summary: CVE-2026-92694 fastnetmon: FastNetMon: Denial of Service via race condition in IPv6 traffic monitoring
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in FastNetMon. A remote attacker could trigger a race condition—a timing conflict where multiple operations access shared data simultaneously—resulting in a Denial of Service (DoS). When processing network traffic within monitored IPv6 ranges, the application updates internal traffic statistics at the same time as screen updates occur without adequate synchronization locking. Under heavy traffic conditions, this unsynchronized access can cause data corruption and potentially crash the monitoring service.
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Description OSIDB Bzimport 2026-11-05 22:42:30 UTC 
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.