Search for vulnerabilities
Vulnerability details: VCID-fq54-3wa1-kkd4
Vulnerability ID VCID-fq54-3wa1-kkd4
Aliases CVE-2021-23965
Summary Mozilla developers Sebastian Hengst, Christian Holler, Tyson Smith reported memory safety bugs present in Firefox 84. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code.
Status Published
Exploitability 0.5
Weighted Severity 8.0
Risk 4.0
Affected and Fixed Packages Package Details
Weaknesses (1)
CWE-787 Out-of-bounds Write
System Score Found at
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23965
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23965
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23965
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23965
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23965
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23965
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23965
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23965
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23965
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23965
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23965
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23965
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23965
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23965
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23965
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23965
epss 0.00372 https://api.first.org/data/v1/epss?cve=CVE-2021-23965
cvssv2 6.8 https://nvd.nist.gov/vuln/detail/CVE-2021-23965
cvssv3.1 8.8 https://nvd.nist.gov/vuln/detail/CVE-2021-23965
archlinux High https://security.archlinux.org/AVG-1492
generic_textual high https://www.mozilla.org/en-US/security/advisories/mfsa2021-03
Reference id Reference type URL
https://api.first.org/data/v1/epss?cve=CVE-2021-23965
https://bugzilla.mozilla.org/buglist.cgi?bug_id=1670378%2C1673555%2C1676812%2C1678582%2C1684497
https://www.mozilla.org/security/advisories/mfsa2021-03/
ASA-202102-1 https://security.archlinux.org/ASA-202102-1
AVG-1492 https://security.archlinux.org/AVG-1492
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
CVE-2021-23965 https://nvd.nist.gov/vuln/detail/CVE-2021-23965
mfsa2021-03 https://www.mozilla.org/en-US/security/advisories/mfsa2021-03
USN-4717-1 https://usn.ubuntu.com/4717-1/
No exploits are available.
Vector: AV:N/AC:M/Au:N/C:P/I:P/A:P Found at https://nvd.nist.gov/vuln/detail/CVE-2021-23965
Exploitability (E) Access Vector (AV) Access Complexity (AC) Authentication (Au) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

high

functional

unproven

proof_of_concept

not_defined

local

adjacent_network

network

high

medium

low

multiple

single

none

none

partial

complete

none

partial

complete

none

partial

complete
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Found at https://nvd.nist.gov/vuln/detail/CVE-2021-23965
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Exploit Prediction Scoring System (EPSS)
Percentile 0.58153
EPSS Score 0.00372
Published At July 30, 2025, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2025-07-31T08:09:50.529753+00:00 Mozilla Importer Import https://github.com/mozilla/foundation-security-advisories/blob/master/announce/2021/mfsa2021-03.yml 37.0.0