Attacker Value
Unknown
(0 users assessed)
Exploitability
Unknown
(0 users assessed)
User Interaction
Required
Privileges Required
None
Attack Vector
Network
0

CVE-2021-32677

Disclosure Date: June 09, 2021 •
CVE-2021-32677 CVSS v3 Base Score: 8.1
Add MITRE ATT&CK tactics and techniques that apply to this CVE.

Description

FastAPI is a web framework for building APIs with Python 3.6+ based on standard Python type hints. FastAPI versions lower than 0.65.2 that used cookies for authentication in path operations that received JSON payloads sent by browsers were vulnerable to a Cross-Site Request Forgery (CSRF) attack. In versions lower than 0.65.2, FastAPI would try to read the request payload as JSON even if the content-type header sent was not set to application/json or a compatible JSON media type (e.g. application/geo+json). A request with a content type of text/plain containing JSON data would be accepted and the JSON data would be extracted. Requests with content type text/plain are exempt from CORS preflights, for being considered Simple requests. The browser will execute them right away including cookies, and the text content could be a JSON string that would be parsed and accepted by the FastAPI application. This is fixed in FastAPI 0.65.2. The request data is now parsed as JSON only if the content-type header is application/json or another JSON compatible media type like application/geo+json. It’s best to upgrade to the latest FastAPI, but if updating is not possible then a middleware or a dependency that checks the content-type header and aborts the request if it is not application/json or another JSON compatible content type can act as a mitigating workaround.

Add Assessment

No one has assessed this topic. Be the first to add your voice to the community.

CVSS V3 Severity and Metrics
Base Score:
8.1 High
Impact Score:
5.2
Exploitability Score:
2.8
Vector:
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
Attack Vector (AV):
Network
Attack Complexity (AC):
Low
Privileges Required (PR):
None
User Interaction (UI):
Required
Scope (S):
Unchanged
Confidentiality (C):
High
Integrity (I):
High
Availability (A):
None

General Information

Offensive Application
Unknown
Utility Class
Unknown
Ports
Unknown
OS
Unknown
Vulnerable Versions
fastapi < 0.65.2
Prerequisites
Unknown
Discovered By
Unknown
PoC Author
Unknown
Metasploit Module
Unknown
Reporter
Unknown

Vendors

  • fedoraproject,
  • tiangolo

Products

  • fastapi,
  • fedora 34
Technical Analysis