CVE intelligence and bounded remediation
CVE-2021-41265 — Flask-AppBuilder is a development framework built on top of Flask
Flask-AppBuilder is a development framework built on top of Flask. Verions prior to 3.3.4 contain an improper authentication vulnerability in the REST API. The issue allows for a malicious actor with a carefully crafted request to successfully authenticate and gain access to existing protected REST API endpoints. This only affects non database authentication types and new REST API endpoints. Users should upgrade to Flask-AppBuilder 3.3.4 to receive a patch.
- Severity
- High
- CVSS
- 8.8 (3.1)
- Published
- 2021-12-09
- CISA KEV
- Not currently listed
- Ecosystem
- software/application
- Weaknesses
- CWE-287
Affected products
- dpgaspar / flask-appbuilder
Matched remediation archetype
Authentication bypass and missing authentication
This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.
Check exposure
- Map every affected endpoint and protocol path, including alternate ports, legacy routes, recovery flows, service accounts, and machine-to-machine access.
- Confirm which deployments enable the affected authentication mode and whether the interface is reachable from untrusted networks.
- Review session, token, credential, and proxy trust configuration without attempting account takeover.
Remediate safely
- Apply the supported fix and centralize fail-closed authentication before protected request handling.
- Remove default or embedded credentials, rotate affected secrets and sessions, and bind authentication decisions to the intended audience and channel.
- Add negative tests for alternate routes, malformed or absent credentials, recovery flows, and proxy-derived identity.
Authoritative sources
Complete CVE record and remediation plan
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