No exploitation reportedFix available

CVE-2021-41265

Q: Is CVE-2021-41265 actively exploited?

Active exploitation of CVE-2021-41265 has not been confirmed. Its EPSS score was 1.3% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2021-41265?

CVE-2021-41265 has a CVSS v3 base score of 8.8 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

No exploitation reported by the sources we read.

Published2021-12-09
Fixed in3.3.4
WeaknessCWE-287

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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.

Timeline

dates in UTC

2021-12-0917:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-41265?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-41265?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV

Dpgaspar flask-appbuilder

Branch	Affected	Fixed in	Source
3.3	< 3.3.4	3.3.4	NVD · OSV

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Dpgaspar flask-appbuilder to 3.3.4

Advisories and patches

github.comPatch
github.comRelease Notes

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

CNACVSS 3.18.1read 2026-10-23
NVDCVSS 3.18.8read 2026-10-23
NVDCVSS 2.06.5read 2026-10-23
CNAweakness (CWE)CWE-287read 2026-10-23
FIRST EPSSEPSS score1.3 %2026-10-23
OSVaffected packages—

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Published: 2021-12-09
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-41265?

Is CVE-2021-41265 actively exploited?

Active exploitation of CVE-2021-41265 has not been confirmed. Its EPSS score was 1.3% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-41265?

CVE-2021-41265 has a CVSS v3 base score of 8.8 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

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