Is CVE-2021-23995 in the CISA KEV catalog?

No. CVE-2021-23995 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-23995?

CVE-2021-23995 has a CVSS v3 base score of 8.8 (HIGH).

What is the EPSS score for CVE-2021-23995?

CVE-2021-23995 has an EPSS score of 1.21% (65th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-23995?

Upgrade firefox on debian unstable to 88.0-1 or later. Fixes are available for 7 affected products.

CVE & CISA-KEV Catalog

CVE-2021-23995

HIGH

8.8

CVSS v3

NVD

Description

When Responsive Design Mode was enabled, it used references to objects that were previously freed. We presume that with enough effort this could have been exploited to run arbitrary code. This vulnerability affects Firefox ESR < 78.10, Thunderbird < 78.10, and Firefox < 88.

CWE-672

How to fix

Remediation Available

firefoxDebian

Fixed in:88.0-1CVE-2021-23995

firefoxUbuntu

Fixed in:88.0+build2-0ubuntu0.16.04.1USN-4926-1

Fixed in:88.0+build2-0ubuntu0.18.04.2USN-4926-1

Fixed in:88.0+build2-0ubuntu0.20.04.1USN-4926-1

thunderbirdUbuntu

Fixed in:1:78.11.0+build1-0ubuntu0.18.04.2USN-4995-2

Fixed in:1:78.11.0+build1-0ubuntu0.20.04.2USN-4995-1

DeveloperEditionWindows application

Affected:88.0Fixed in:88.0Mozilla

Mozilla Firefox (en-US)Windows application

Affected:88.0Fixed in:88.0Mozilla

Mozilla Firefox ESR (en-US)Windows application

Affected:78.10Fixed in:78.10Mozilla

Mozilla Thunderbird (en-US)Windows application

Affected:78.10Fixed in:78.10Mozilla

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

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

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

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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.