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Vulnerability details: VCID-wazb-a3n1-h7b5
Vulnerability ID VCID-wazb-a3n1-h7b5
Aliases CVE-2021-23995
Summary 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.
Status Published
Exploitability 0.5
Weighted Severity 8.0
Risk 4.0
Affected and Fixed Packages Package Details
Weaknesses (2)
CWE-416 Use After Free
CWE-672 Operation on a Resource after Expiration or Release
System Score Found at
cvssv3 8.8 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-23995.json
epss 0.01023 https://api.first.org/data/v1/epss?cve=CVE-2021-23995
epss 0.01023 https://api.first.org/data/v1/epss?cve=CVE-2021-23995
epss 0.01023 https://api.first.org/data/v1/epss?cve=CVE-2021-23995
epss 0.01023 https://api.first.org/data/v1/epss?cve=CVE-2021-23995
epss 0.01023 https://api.first.org/data/v1/epss?cve=CVE-2021-23995
epss 0.01023 https://api.first.org/data/v1/epss?cve=CVE-2021-23995
epss 0.01023 https://api.first.org/data/v1/epss?cve=CVE-2021-23995
epss 0.01023 https://api.first.org/data/v1/epss?cve=CVE-2021-23995
epss 0.01023 https://api.first.org/data/v1/epss?cve=CVE-2021-23995
epss 0.01023 https://api.first.org/data/v1/epss?cve=CVE-2021-23995
epss 0.01023 https://api.first.org/data/v1/epss?cve=CVE-2021-23995
epss 0.01023 https://api.first.org/data/v1/epss?cve=CVE-2021-23995
epss 0.01023 https://api.first.org/data/v1/epss?cve=CVE-2021-23995
epss 0.01023 https://api.first.org/data/v1/epss?cve=CVE-2021-23995
epss 0.01023 https://api.first.org/data/v1/epss?cve=CVE-2021-23995
epss 0.01023 https://api.first.org/data/v1/epss?cve=CVE-2021-23995
epss 0.01114 https://api.first.org/data/v1/epss?cve=CVE-2021-23995
cvssv3.1 7.5 https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
cvssv2 5.1 https://nvd.nist.gov/vuln/detail/CVE-2021-23995
cvssv3.1 8.8 https://nvd.nist.gov/vuln/detail/CVE-2021-23995
archlinux High https://security.archlinux.org/AVG-1834
archlinux High https://security.archlinux.org/AVG-1836
generic_textual high https://www.mozilla.org/en-US/security/advisories/mfsa2021-14
generic_textual high https://www.mozilla.org/en-US/security/advisories/mfsa2021-15
generic_textual high https://www.mozilla.org/en-US/security/advisories/mfsa2021-16
Reference id Reference type URL
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-23995.json
https://api.first.org/data/v1/epss?cve=CVE-2021-23995
https://bugzilla.mozilla.org/show_bug.cgi?id=1699835
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-23961
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-23991
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-23992
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-23993
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-23994
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-23995
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-23998
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-23999
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-24002
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-29945
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-29946
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-29948
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-29949
https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
https://www.mozilla.org/security/advisories/mfsa2021-14/
https://www.mozilla.org/security/advisories/mfsa2021-15/
https://www.mozilla.org/security/advisories/mfsa2021-16/
1951365 https://bugzilla.redhat.com/show_bug.cgi?id=1951365
ASA-202104-3 https://security.archlinux.org/ASA-202104-3
ASA-202104-4 https://security.archlinux.org/ASA-202104-4
AVG-1834 https://security.archlinux.org/AVG-1834
AVG-1836 https://security.archlinux.org/AVG-1836
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:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
CVE-2021-23995 https://nvd.nist.gov/vuln/detail/CVE-2021-23995
mfsa2021-14 https://www.mozilla.org/en-US/security/advisories/mfsa2021-14
mfsa2021-15 https://www.mozilla.org/en-US/security/advisories/mfsa2021-15
mfsa2021-16 https://www.mozilla.org/en-US/security/advisories/mfsa2021-16
RHSA-2021:1350 https://access.redhat.com/errata/RHSA-2021:1350
RHSA-2021:1351 https://access.redhat.com/errata/RHSA-2021:1351
RHSA-2021:1352 https://access.redhat.com/errata/RHSA-2021:1352
RHSA-2021:1353 https://access.redhat.com/errata/RHSA-2021:1353
RHSA-2021:1360 https://access.redhat.com/errata/RHSA-2021:1360
RHSA-2021:1361 https://access.redhat.com/errata/RHSA-2021:1361
RHSA-2021:1362 https://access.redhat.com/errata/RHSA-2021:1362
RHSA-2021:1363 https://access.redhat.com/errata/RHSA-2021:1363
USN-4926-1 https://usn.ubuntu.com/4926-1/
USN-4995-1 https://usn.ubuntu.com/4995-1/
USN-4995-2 https://usn.ubuntu.com/4995-2/
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-23995.json
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
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H Found at https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
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
Vector: AV:N/AC:H/Au:N/C:P/I:P/A:P Found at https://nvd.nist.gov/vuln/detail/CVE-2021-23995
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-2021-23995
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 0.76335
EPSS Score 0.01023
Published At July 30, 2025, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2025-07-31T08:09:45.465224+00:00 Mozilla Importer Import https://github.com/mozilla/foundation-security-advisories/blob/master/announce/2021/mfsa2021-15.yml 37.0.0