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

Status: published. Published: 2026-11-05. Updated: 2026-11-05.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- pavel-odintsov / fastnetmon: <= 1.2.9 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- CVSS 3.1: 5.9 (medium); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-362

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/pavel-odintsov/fastnetmon/security/advisories/GHSA-phrw-2q76-5m7h (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/pavel-odintsov/fastnetmon/pull/1087 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/pavel-odintsov/fastnetmon/commit/1294724ea931dc78fe545360f2193398bba35381 (CNA: GitHub_M; x_refsource_MISC)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-92694; retrieved 2026-11-05; source updated 2026-11-05

Revision: 686c8239301fddc968807666a9582035f1b51645fcfa28ccf86c018e77e359b7

Canonical: https://y2.dev/cve/CVE-2026-92694

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