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Vulnerability details: VCID-4veh-4gqw-6yh4
Vulnerability ID VCID-4veh-4gqw-6yh4
Aliases CVE-2020-26959
Summary During browser shutdown, reference decrementing could have occured on a previously freed object, resulting in a use-after-free, memory corruption, and a potentially exploitable crash.
Status Published
Exploitability 0.5
Weighted Severity 9.0
Risk 4.5
Affected and Fixed Packages Package Details
Weaknesses (1)
CWE-416 Use After Free
System Score Found at
cvssv3 8.8 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2020-26959.json
epss 0.00495 https://api.first.org/data/v1/epss?cve=CVE-2020-26959
epss 0.00495 https://api.first.org/data/v1/epss?cve=CVE-2020-26959
epss 0.00495 https://api.first.org/data/v1/epss?cve=CVE-2020-26959
epss 0.00495 https://api.first.org/data/v1/epss?cve=CVE-2020-26959
epss 0.00495 https://api.first.org/data/v1/epss?cve=CVE-2020-26959
epss 0.00495 https://api.first.org/data/v1/epss?cve=CVE-2020-26959
epss 0.00495 https://api.first.org/data/v1/epss?cve=CVE-2020-26959
epss 0.00495 https://api.first.org/data/v1/epss?cve=CVE-2020-26959
epss 0.00495 https://api.first.org/data/v1/epss?cve=CVE-2020-26959
epss 0.00495 https://api.first.org/data/v1/epss?cve=CVE-2020-26959
epss 0.00495 https://api.first.org/data/v1/epss?cve=CVE-2020-26959
epss 0.00495 https://api.first.org/data/v1/epss?cve=CVE-2020-26959
epss 0.00495 https://api.first.org/data/v1/epss?cve=CVE-2020-26959
epss 0.00495 https://api.first.org/data/v1/epss?cve=CVE-2020-26959
epss 0.00495 https://api.first.org/data/v1/epss?cve=CVE-2020-26959
epss 0.00495 https://api.first.org/data/v1/epss?cve=CVE-2020-26959
epss 0.00495 https://api.first.org/data/v1/epss?cve=CVE-2020-26959
epss 0.00495 https://api.first.org/data/v1/epss?cve=CVE-2020-26959
cvssv3.1 8.8 https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
cvssv2 6.8 https://nvd.nist.gov/vuln/detail/CVE-2020-26959
cvssv3.1 8.8 https://nvd.nist.gov/vuln/detail/CVE-2020-26959
archlinux Critical https://security.archlinux.org/AVG-1279
generic_textual high https://www.mozilla.org/en-US/security/advisories/mfsa2020-50
generic_textual high https://www.mozilla.org/en-US/security/advisories/mfsa2020-51
generic_textual high https://www.mozilla.org/en-US/security/advisories/mfsa2020-52
Reference id Reference type URL
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2020-26959.json
https://api.first.org/data/v1/epss?cve=CVE-2020-26959
https://bugzilla.mozilla.org/show_bug.cgi?id=1669466
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-16012
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-26951
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-26953
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-26956
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-26958
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-26959
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-26960
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-26961
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-26965
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-26968
https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
https://www.mozilla.org/security/advisories/mfsa2020-50/
https://www.mozilla.org/security/advisories/mfsa2020-51/
https://www.mozilla.org/security/advisories/mfsa2020-52/
1898736 https://bugzilla.redhat.com/show_bug.cgi?id=1898736
ASA-202011-12 https://security.archlinux.org/ASA-202011-12
AVG-1279 https://security.archlinux.org/AVG-1279
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-2020-26959 https://nvd.nist.gov/vuln/detail/CVE-2020-26959
mfsa2020-50 https://www.mozilla.org/en-US/security/advisories/mfsa2020-50
mfsa2020-51 https://www.mozilla.org/en-US/security/advisories/mfsa2020-51
mfsa2020-52 https://www.mozilla.org/en-US/security/advisories/mfsa2020-52
RHSA-2020:5231 https://access.redhat.com/errata/RHSA-2020:5231
RHSA-2020:5232 https://access.redhat.com/errata/RHSA-2020:5232
RHSA-2020:5233 https://access.redhat.com/errata/RHSA-2020:5233
RHSA-2020:5234 https://access.redhat.com/errata/RHSA-2020:5234
RHSA-2020:5235 https://access.redhat.com/errata/RHSA-2020:5235
RHSA-2020:5236 https://access.redhat.com/errata/RHSA-2020:5236
RHSA-2020:5237 https://access.redhat.com/errata/RHSA-2020:5237
RHSA-2020:5238 https://access.redhat.com/errata/RHSA-2020:5238
RHSA-2020:5239 https://access.redhat.com/errata/RHSA-2020:5239
RHSA-2020:5240 https://access.redhat.com/errata/RHSA-2020:5240
RHSA-2020:5257 https://access.redhat.com/errata/RHSA-2020:5257
RHSA-2020:5314 https://access.redhat.com/errata/RHSA-2020:5314
USN-4637-1 https://usn.ubuntu.com/4637-1/
USN-4637-2 https://usn.ubuntu.com/4637-2/
USN-4647-1 https://usn.ubuntu.com/4647-1/
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-2020-26959.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:L/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:M/Au:N/C:P/I:P/A:P Found at https://nvd.nist.gov/vuln/detail/CVE-2020-26959
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-2020-26959
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 0.64739
EPSS Score 0.00495
Published At July 30, 2025, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2025-07-31T08:09:42.270884+00:00 Mozilla Importer Import https://github.com/mozilla/foundation-security-advisories/blob/master/announce/2020/mfsa2020-51.yml 37.0.0