Tested fixes for CWE-287 in Express, Flask, Spring Boot, ASP.NET Core, Next.js, FastAPI, Django, net/http, Rails and Laravel: the vulnerable code, the fix, a plausible fix that still fails, and the regression tests.
The description above is MITRE’s definition of CWE-287 in CWE 4.20, a class-level weakness.
Common consequences MITRE lists
- Integrity, Confidentiality, Availability, Access Control: Read Application Data; Gain Privileges or Assume Identity; Execute Unauthorized Code or Commands
Guides on this site
Defend JWTs against forgery, confusion and replay
Verify a JWT as an issuer-, type- and audience-bound assertion with an algorithm allowlist and trusted keys, closing the alg "none", key-confusion, header-injection, weak-secret and replay attacks.
Defend OAuth and OIDC against redirect and token attacks
Apply RFC 9700 and RFC 10017: exact redirect matching, PKCE with downgrade protection, state and iss binding, refresh-token rotation, sender-constrained tokens, and a backend-for-frontend so browser tokens cannot be stolen.
Practice
References
This page is generated from MITRE’s CWE 4.20 catalogue (released 30 April 2026) and lists every guide, fix card and lab here that cites CWE-287.
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