CVE-2021-23995

Q: How do I fix CVE-2021-23995?

Published advisories record a fix for 7 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.

Q: Is CVE-2021-23995 being actively exploited?

Not that we know of. CVE-2021-23995 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 1.2% is the estimated probability that it will be exploited in the next 30 days. That is higher than 66% of all scored CVEs.

Q: How severe is CVE-2021-23995?

CVE-2021-23995 has a CVSS v3 base score of 8.8, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

Q: What does CVE-2021-23995 affect?

Published advisories record a fix for firefox (Debian), firefox (Ubuntu), thunderbird (Ubuntu), DeveloperEdition (Windows application), and 3 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

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

66thpercentile

Moderate risk: more likely to be exploited than 66% of all known CVEs.

References

Vendor Advisory4

Related Vulnerabilities

Other CWE-672 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-23638	Medium	6.5	60%	-	Fix
CVE-2020-11027	Medium	6.1	14%	-	Fix
CVE-2019-17638	Critical	9.4	11%	-	Fix
CVE-2009-3547	High	7.0	4.9%	-	-
CVE-2019-15691	High	7.2	4.7%	-	Fix
CVE-2020-24030	Critical	9.8	2.7%	-	-

Common questions

How do I fix CVE-2021-23995?

Published advisories record a fix for 7 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.

Is CVE-2021-23995 being actively exploited?

Not that we know of. CVE-2021-23995 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 1.2% is the estimated probability that it will be exploited in the next 30 days. That is higher than 66% of all scored CVEs.

How severe is CVE-2021-23995?

CVE-2021-23995 has a CVSS v3 base score of 8.8, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2021-23995 affect?

Published advisories record a fix for firefox (Debian), firefox (Ubuntu), thunderbird (Ubuntu), DeveloperEdition (Windows application), and 3 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

Embed a live status badge for CVE-2021-23995

Markdown

[![CVE-2021-23995](https://tridentstack.com/cve/badge/CVE-2021-23995.svg)](https://tridentstack.com/cve/CVE-2021-23995)

HTML

<a href="https://tridentstack.com/cve/CVE-2021-23995"><img src="https://tridentstack.com/cve/badge/CVE-2021-23995.svg" alt="CVE-2021-23995"></a>

Find and fix vulnerabilities across your fleet

TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.

See how it works Start freeThis CVE lookup is free and always will be.

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.