How severe is CVE-2021-23385?

CVE-2021-23385 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2021-23385 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (56th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-23385?

CVE-2021-23385 affects Flask-security Project Flask-security. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-23385?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-23385 published?

CVE-2021-23385 was published on 2022-08-02 and last updated on 2026-06-17.

CVE-2021-23385

CVE-2021-23385 is a medium-severity vulnerability in Flask-security Project Flask-security with a CVSS 3.x base score of 5.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-601.

Key facts

Severity: Medium (CVSS 3.x base score 5.4)
EPSS exploit prediction: 1% (56th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-601
Affected product: Flask-security Project Flask-security
Published: 2022-08-02
Last modified: 2026-06-17

Description

This affects all versions of package Flask-Security. When using the get_post_logout_redirect and get_post_login_redirect functions, it is possible to bypass URL validation and redirect a user to an arbitrary URL by providing multiple back slashes such as \\\evil.com/path. This vulnerability is only exploitable if an alternative WSGI server other than Werkzeug is used, or the default behaviour of Werkzeug is modified using 'autocorrect_location_header=False. **Note:** Flask-Security is not maintained anymore.

Frequently asked questions

What is CVE-2021-23385?: This affects all versions of package Flask-Security. When using the get_post_logout_redirect and get_post_login_redirect functions, it is possible to bypass URL validation and redirect a user to an arbitrary URL by providing multiple back slashes such as \\\evil.com/path. This vulnerability is only exploitable if an alternative WSGI server other than Werkzeug is used, or the default behaviour of Werkzeug is modified using 'autocorrect_location_header=False. **Note:** Flask-Security is not maintained anymore.
How severe is CVE-2021-23385?: CVE-2021-23385 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2021-23385 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (56th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-23385?: CVE-2021-23385 affects Flask-security Project Flask-security. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-23385?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-23385 published?: CVE-2021-23385 was published on 2022-08-02 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:flask-security_project:flask-security:*:*:*:*:*:*:*:*

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