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Medium6.9Fortinet

Medium [CVE-2025-53843] stack-based buffer overflow vulnerability in Fortinet FortiOS 7.6.0 through 7.6.3, FortiOS 7.4.0 through 7.4.8, FortiOS 7.2…

This medium-severity Fortinet advisory covers CVE-2025-53843 affecting FortiOS.

CVE-2025-53843 Published Nov 18, 2025Updated by vendor Nov 21, 2025
Affected products & platforms
FortinetFortiGateFirewallFortiOS
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Summary

A stack-based buffer overflow vulnerability in Fortinet FortiOS 7.6.0 through 7.6.3, FortiOS 7.4.0 through 7.4.8, FortiOS 7.2 all versions, FortiOS 7.0 all versions, FortiOS 6.4 all versions allows attacker to execute unauthorized code or commands via specially crafted packets

Affected versions
  • FortiOS 7.6: 7.6.0 through 7.6.3
  • FortiOS 7.4: 7.4.0 through 7.4.8
  • FortiOS 7.2: 7.2 all versions
  • FortiOS 7.0: 7.0 all versions
  • FortiOS 6.4: 6.4 all versions

Official advisory · high-confidence parse· fetched 9 days ago·verify at source

Fixed versions
  • FortiOS 7.6: 7.6.4
  • FortiOS 7.4: 7.4.9
  • FortiOS 7.2: migrate to a fixed release
  • FortiOS 7.0: migrate to a fixed release
  • FortiOS 6.4: migrate to a fixed release

Official advisory · high-confidence parse· fetched 9 days ago·verify at source

Mitigation checklist

Recommended fix / mitigation
  • Upgrade per the Affected/Solution table: FortiOS 7.6: 7.6.4; FortiOS 7.4: 7.4.9; FortiOS 7.2: migrate to a fixed release; FortiOS 7.0: migrate to a fixed release; FortiOS 6.4: migrate to a fixed release.
Temporary workarounds
  • Warning :if auto-auth-extension-device is enable in config system interface, any devicecan be authorized and then the vulnerability can be exploited without administratorauthorization.Please note that auto-auth-extension-device is disabled by default

Official advisory · high-confidence parse· fetched 9 days ago·verify at source

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