CWE-692: Incomplete Denylist to Cross-Site Scripting
The product uses a denylist-based protection mechanism to defend against XSS attacks, but the denylist is incomplete, allowing XSS variants to succeed.
How it's found
Incomplete Denylist to Cross-Site Scripting only appears when several contributing weaknesses combine. Testers look for each contributing condition separately, then chain them together to confirm the combined weakness is actually reachable and exploitable.
While XSS might seem simple to prevent, web browsers vary so widely in how they parse web pages, that a denylist cannot keep track of all the variations. The "XSS Cheat Sheet" [REF-714] contains a large number of attacks that are intended to bypass incomplete denylists.
Consequences
- Execute Unauthorized Code or Commands
Where this fits in a TurboPentest engagement
This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.
Frequently asked questions
What is CWE-692?
The product uses a denylist-based protection mechanism to defend against XSS attacks, but the denylist is incomplete, allowing XSS variants to succeed.
How do you find Incomplete Denylist to Cross-Site Scripting?
Incomplete Denylist to Cross-Site Scripting only appears when several contributing weaknesses combine. Testers look for each contributing condition separately, then chain them together to confirm the combined weakness is actually reachable and exploitable.
What is the impact of CWE-692?
Execute Unauthorized Code or Commands
Does TurboPentest test for Incomplete Denylist to Cross-Site Scripting?
This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.
Related CWEs
Written and reviewed by
Michel Chamberland - Founder & CEO, IntegSec
CISSP, OSCP, OSCE, CEH, GIAC, CCSK · 20+ years in offensive security
Michel has spent 20+ years on offensive security teams including IBM X-Force Red and Trustwave SpiderLabs, leading penetration tests, red team engagements, and breach response for Fortune 500 customers. He is the founder of IntegSec and the architect of TurboPentest.
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