CVE-2021-21241

HIGHNVD 7.47.4—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.4 under NVD CVSS v3. EPSS exploit probability: 0.9%, top 44% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
7.4EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 7.4Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

The Python "Flask-Security-Too" package is used for adding security features to your Flask application. It is an is a independently maintained version of Flask-Security based on the 3.0.0 version of Flask-Security. In Flask-Security-Too from version 3.3.0 and before version 3.4.5, the /login and /change endpoints can return the authenticated user's authentication token in response to a GET request. Since GET requests aren't protected with a CSRF token, this could lead to a malicious 3rd party site acquiring the authentication token. Version 3.4.5 and version 4.0.0 are patched. As a workaround, if you aren't using authentication tokens - you can set the SECURITY_TOKEN_MAX_AGE to "0" (seconds) which should make the token unusable.

CVSS v3
7.4
EG Score
7.4(medium)
EG Risk
38(Track)
EG Risk 38/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity74% × 45%
Exploitation1% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
59%
KEV
Not listed

Published

January 11, 2021

Last Modified

November 21, 2024

References (12)

Affected Packages

(5 across 5 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
flask-security—4.0.0-1—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
flask-security—4.0.0-1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
flask-security—4.0.0-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
flask-security—4.0.0-1—
PyPI(1)
PackageVulnerable rangeFixed inDependents
flask-security-too3.3.0 ... 3.4.4 (9 versions)3.4.5—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 7× in last 7d / 29× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 160 total refreshes for this CVE.

  1. 2026-09-19 15:37 UTCEPSS rescore
  2. 2026-09-18 19:23 UTCEPSS rescore
  3. 2026-09-17 19:23 UTCEPSS rescore
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  13. 2026-09-07 01:18 UTCOSV refresh
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  1. 2026-08-26 14:42 UTCEPSS rescore
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  3. 2026-08-23 00:16 UTCEPSS rescore
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  5. 2026-08-20 22:52 UTCEPSS rescore
  6. 2026-08-20 11:01 UTCOSV refresh
  7. 2026-08-19 17:01 UTCEPSS rescore
  8. 2026-08-18 13:45 UTCEPSS rescore
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  20. 2026-08-05 19:14 UTCEPSS rescore
  21. 2026-08-05 06:11 UTCOSV refresh
  22. 2026-08-04 15:06 UTCEPSS rescore
  23. 2026-08-04 10:34 UTCEPSS rescore
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  27. 2026-07-30 16:25 UTCEPSS rescore
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  33. 2026-07-23 14:15 UTCEPSS rescore
  34. 2026-07-23 01:57 UTCEG score recompute
  35. 2026-07-22 22:43 UTCEG score recompute
  36. 2026-07-22 14:05 UTCEPSS rescore
  37. 2026-07-21 15:22 UTCEPSS rescore
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  39. 2026-07-20 17:04 UTCEPSS rescore
  40. 2026-07-19 14:28 UTCEPSS rescore
  41. 2026-07-19 04:22 UTCOSV refresh
  42. 2026-07-19 02:26 UTCEPSS rescore
  43. 2026-07-18 10:02 UTCEPSS rescore
  44. 2026-07-16 17:00 UTCEPSS rescore
  45. 2026-07-15 16:55 UTCEPSS rescore
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  48. 2026-07-13 22:27 UTCEPSS rescore
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  54. 2026-07-11 08:25 UTCEPSS rescore
  55. 2026-07-09 19:07 UTCEPSS rescore
  56. 2026-07-08 15:12 UTCEPSS rescore
  57. 2026-07-07 13:43 UTCEPSS rescore
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  63. 2026-07-04 06:29 UTCEPSS rescore
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  65. 2026-07-02 16:57 UTCEPSS rescore
  66. 2026-07-01 15:03 UTCEPSS rescore
  67. 2026-07-01 11:18 UTCOSV refresh
  68. 2026-06-30 23:20 UTCEPSS rescore
  69. 2026-06-30 23:20 UTCEPSS rescore
  70. 2026-06-29 14:04 UTCEPSS rescore
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  72. 2026-06-28 14:05 UTCEPSS rescore
  73. 2026-06-28 04:54 UTCEPSS rescore
  74. 2026-06-28 04:54 UTCEPSS rescore
  75. 2026-06-27 03:06 UTCEPSS rescore

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2021-21241?
CVE-2021-21241 is a high vulnerability published on January 11, 2021. The Python "Flask-Security-Too" package is used for adding security features to your Flask application. It is an is a independently maintained version of Flask-Security based on the 3.0.0 version of Flask-Security. In Flask-Security-Too from version 3.3.0 and before version 3.4.5, the /login and…
When was CVE-2021-21241 disclosed?
CVE-2021-21241 was first published in the National Vulnerability Database on January 11, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-21241 actively exploited?
CVE-2021-21241 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 41.3% of all scored CVEs.
What is the CVSS score of CVE-2021-21241?
CVE-2021-21241 has a CVSS v3 base score of 7.4 (NVD).
How do I remediate CVE-2021-21241?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-21241, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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