HOMEVULNERABILITIESCVE-2021-23997
HIGH

CVE-2021-23997

CWE-681Published: June 24, 2021· Updated: Jun 17, 2026

8.8
CVSS v3.1

Official Description

Due to unexpected data type conversions, a use-after-free could have occurred when interacting with the font cache. We presume that with enough effort this could have been exploited to run arbitrary code. This vulnerability affects Firefox < 88.

NVD Source

Technical Analysis

CVE-2021-23997 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation does not require any privileges, though user interaction (Required) is needed, which slightly reduces the risk of mass automated attacks.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 8.8.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
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

Affected Vendors & Products

Mozilla1 product(s)
firefox
Source: NVD CPE · 1 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

ADVISORYhttps://bugzilla.mozilla.org/show_bug.cgi?id=1701942
ADVISORYhttps://www.mozilla.org/security/advisories/mfsa2021-16/
ADVISORYhttps://bugzilla.mozilla.org/show_bug.cgi?id=1701942
ADVISORYhttps://www.mozilla.org/security/advisories/mfsa2021-16/

All References (4)

→
https://bugzilla.mozilla.org/show_bug.cgi?id=1701942Issue Tracking · Permissions Required · Vendor Advisory
→
https://www.mozilla.org/security/advisories/mfsa2021-16/Release Notes · Vendor Advisory
→
https://bugzilla.mozilla.org/show_bug.cgi?id=1701942Issue Tracking · Permissions Required · Vendor Advisory
→
https://www.mozilla.org/security/advisories/mfsa2021-16/Release Notes · Vendor Advisory

Quick Facts

CVE IDCVE-2021-23997
CVSS Score8.8 / 10
SeverityHIGH
WeaknessCWE-681
CISA KEVNo
Affected1 vendor(s)
PublishedJun 24, 2021

Related CVEs (CWE-681)

CVE-2019-19317
9.8
CVE-2016-3074
9.8
CVE-2019-14842
9.8
CVE-2022-40138
9.8
CVE-2021-36357
9.8
CVE-2021-38187
9.8

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-23997 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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