Japan's SiteGuard WAF flaw CVE-2026-106931 is already being exploited

SiteGuard flaw under active attack. Attackers exploit CVE-2026-106931 in SiteGuard Server Edition to run commands as root or SYSTEM. The OS command injection bug affects the statistics feature enabled by default in versions 2.20 and later. Successful exploitation gives full control of the server. The vendor offers a patch that replaces statistics processing files and advises saving diagnostic information before updating.

Zero Day Brief #24 · 20 Oct 2026

Sources

• Security Affairs

Story so far

1. 2026-10-15 Fake Arch Linux packages push malware with root privileges – BleepingComputer
   first report
2. 2026-10-16 Fake Arch Linux AUR packages exploit typos to run malware with root privileges – Help Net Security
3. 2026-10-18 Hackers exploit SiteGuard WAF flaw to run commands as SYSTEM, root – BleepingComputer
4. 2026-10-19 Japan's SiteGuard WAF flaw CVE-2026-106931 is already being exploited – Security Affairs
   exploited in attacks

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