Is CVE-2021-23393 in the CISA KEV catalog?

No. CVE-2021-23393 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-23393?

CVE-2021-23393 has a CVSS v3 base score of 5.4 (MEDIUM).

What is the EPSS score for CVE-2021-23393?

CVE-2021-23393 has an EPSS score of 0.72% (49th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-23393?

Upgrade flask unchained to 0.9.0 or later.

CVE & CISA-KEV Catalog

CVE-2021-23393

MEDIUM

5.4

CVSS v3

NVD

Description

This affects the package Flask-Unchained before 0.9.0. When using the the _validate_redirect_url function, 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.

CWE-601Open Redirect

How to fix

Remediation Available

flask unchainedNVD

Affected:< 0.9.0Fixed in:0.9.0CVE-2021-23393derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

Exploit Intelligence

0.72%probability of exploitation in 30 days

49thpercentile

Moderate risk: more likely to be exploited than 49% of all known CVEs.

References

Patch2

Related Vulnerabilities

Other CWE-601 (Open Redirect) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2025-4123	High	7.6	98%	-	Fix
CVE-2018-11784	Medium	4.3	94%	-	Fix
CVE-2021-22881	Medium	6.1	87%	-	Fix
CVE-2022-45402	Medium	6.1	82%	-	Fix
CVE-2017-1000117	High	8.8	78%	-	Fix
CVE-2019-10098	Medium	6.1	74%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.