FortiAuthenticator 6.6.0-8.0.3 Stack Buffer Overflow in FSSO (CVE-2026-126239)
CVE-2026-126239 Published on November 11, 2026
A stack-based buffer overflow vulnerability in Fortinet FortiAuthenticator 8.0.0 through 8.0.3, FortiAuthenticator 6.6.0 through 6.6.10 may allow an unauthenticated attacker to crash the FSSO subsystem via crafted http requests
Vulnerability Analysis
CVE-2026-126239 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.
Weakness Type
What is a Stack Overflow Vulnerability?
A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
CVE-2026-126239 has been classified to as a Stack Overflow vulnerability or weakness.
Products Associated with CVE-2026-126239
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Affected Versions
Fortinet FortiAuthenticator:- Version 8.0.0, <= 8.0.3 is affected.
- Version 6.6.0, <= 6.6.10 is affected.