Is CVE-2021-23968 in the CISA KEV catalog?

No. CVE-2021-23968 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-23968?

CVE-2021-23968 has a CVSS v3 base score of 4.3 (MEDIUM).

What is the EPSS score for CVE-2021-23968?

CVE-2021-23968 has an EPSS score of 1.21% (65th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-23968?

Upgrade firefox on debian unstable to 86.0-1 or later. Fixes are available for 7 affected products.

CVE & CISA-KEV Catalog

CVE-2021-23968

MEDIUM

4.3

CVSS v3

NVD

Description

If Content Security Policy blocked frame navigation, the full destination of a redirect served in the frame was reported in the violation report; as opposed to the original frame URI. This could be used to leak sensitive information contained in such URIs. This vulnerability affects Firefox < 86, Thunderbird < 78.8, and Firefox ESR < 78.8.

CWE-209

How to fix

Remediation Available

firefoxDebian

Fixed in:86.0-1CVE-2021-23968

firefoxUbuntu

Fixed in:86.0+build3-0ubuntu0.16.04.1USN-4756-1

Fixed in:86.0+build3-0ubuntu0.18.04.1USN-4756-1

Fixed in:86.0+build3-0ubuntu0.20.04.1USN-4756-1

thunderbirdUbuntu

Fixed in:1:78.8.1+build1-0ubuntu0.20.04.1USN-4936-1

DeveloperEditionWindows application

Affected:86.0Fixed in:86.0Mozilla

Mozilla Firefox (en-US)Windows application

Affected:86.0Fixed in:86.0Mozilla

Mozilla Firefox ESR (en-US)Windows application

Affected:78.8Fixed in:78.8Mozilla

Mozilla Thunderbird (en-US)Windows application

Affected:78.8Fixed in:78.8Mozilla

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

IntegrityNone

AvailabilityNone

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

Exploit Intelligence

1.21%probability of exploitation in 30 days

65thpercentile

Moderate risk: more likely to be exploited than 65% of all known CVEs.

References

Vendor Advisory4

Third-Party Advisory4

Related Vulnerabilities

Other CWE-209 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-29059	High	7.5	99%	KEV	-
CVE-2021-22145	Medium	6.5	76%	-	-
CVE-2010-3332	Medium	6.4	67%	-	-
CVE-2025-62168	Critical	10.0	63%	-	Fix
CVE-2013-7331	Medium	6.5	58%	KEV	-
CVE-2025-47813	Medium	4.3	56%	KEV	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.