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Vulnerability details: VCID-q8x9-4w5b-43hc
Vulnerability ID VCID-q8x9-4w5b-43hc
Aliases CVE-2020-26974
Summary When flex-basis was used on a table wrapper, a StyleGenericFlexBasis object could have been incorrectly cast to the wrong type. This resulted in a heap user-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 (2)
CWE-787 Out-of-bounds Write
CWE-416 Use After Free
System Score Found at
cvssv3 8.8 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2020-26974.json
epss 0.00535 https://api.first.org/data/v1/epss?cve=CVE-2020-26974
epss 0.00535 https://api.first.org/data/v1/epss?cve=CVE-2020-26974
epss 0.00535 https://api.first.org/data/v1/epss?cve=CVE-2020-26974
epss 0.00535 https://api.first.org/data/v1/epss?cve=CVE-2020-26974
epss 0.00535 https://api.first.org/data/v1/epss?cve=CVE-2020-26974
epss 0.00535 https://api.first.org/data/v1/epss?cve=CVE-2020-26974
epss 0.00535 https://api.first.org/data/v1/epss?cve=CVE-2020-26974
epss 0.00535 https://api.first.org/data/v1/epss?cve=CVE-2020-26974
epss 0.00535 https://api.first.org/data/v1/epss?cve=CVE-2020-26974
epss 0.00535 https://api.first.org/data/v1/epss?cve=CVE-2020-26974
epss 0.00535 https://api.first.org/data/v1/epss?cve=CVE-2020-26974
epss 0.00535 https://api.first.org/data/v1/epss?cve=CVE-2020-26974
epss 0.00535 https://api.first.org/data/v1/epss?cve=CVE-2020-26974
epss 0.00535 https://api.first.org/data/v1/epss?cve=CVE-2020-26974
epss 0.00535 https://api.first.org/data/v1/epss?cve=CVE-2020-26974
epss 0.00535 https://api.first.org/data/v1/epss?cve=CVE-2020-26974
epss 0.00535 https://api.first.org/data/v1/epss?cve=CVE-2020-26974
cvssv3.1 7.5 https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
cvssv2 6.8 https://nvd.nist.gov/vuln/detail/CVE-2020-26974
cvssv3.1 8.8 https://nvd.nist.gov/vuln/detail/CVE-2020-26974
archlinux High https://security.archlinux.org/AVG-1315
archlinux High https://security.archlinux.org/AVG-1362
generic_textual critical https://www.mozilla.org/en-US/security/advisories/mfsa2020-54
generic_textual critical https://www.mozilla.org/en-US/security/advisories/mfsa2020-55
generic_textual critical https://www.mozilla.org/en-US/security/advisories/mfsa2020-56
Reference id Reference type URL
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2020-26974.json
https://api.first.org/data/v1/epss?cve=CVE-2020-26974
https://bugzilla.mozilla.org/show_bug.cgi?id=1681022
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-16042
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-26971
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-26973
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-26974
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-26978
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-35111
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-35113
https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
https://www.mozilla.org/security/advisories/mfsa2020-54/
https://www.mozilla.org/security/advisories/mfsa2020-55/
https://www.mozilla.org/security/advisories/mfsa2020-56/
1908024 https://bugzilla.redhat.com/show_bug.cgi?id=1908024
ASA-202012-23 https://security.archlinux.org/ASA-202012-23
ASA-202012-25 https://security.archlinux.org/ASA-202012-25
AVG-1315 https://security.archlinux.org/AVG-1315
AVG-1362 https://security.archlinux.org/AVG-1362
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-2020-26974 https://nvd.nist.gov/vuln/detail/CVE-2020-26974
mfsa2020-54 https://www.mozilla.org/en-US/security/advisories/mfsa2020-54
mfsa2020-55 https://www.mozilla.org/en-US/security/advisories/mfsa2020-55
mfsa2020-56 https://www.mozilla.org/en-US/security/advisories/mfsa2020-56
RHSA-2020:5561 https://access.redhat.com/errata/RHSA-2020:5561
RHSA-2020:5562 https://access.redhat.com/errata/RHSA-2020:5562
RHSA-2020:5563 https://access.redhat.com/errata/RHSA-2020:5563
RHSA-2020:5564 https://access.redhat.com/errata/RHSA-2020:5564
RHSA-2020:5565 https://access.redhat.com/errata/RHSA-2020:5565
RHSA-2020:5618 https://access.redhat.com/errata/RHSA-2020:5618
RHSA-2020:5622 https://access.redhat.com/errata/RHSA-2020:5622
RHSA-2020:5624 https://access.redhat.com/errata/RHSA-2020:5624
RHSA-2020:5644 https://access.redhat.com/errata/RHSA-2020:5644
RHSA-2020:5645 https://access.redhat.com/errata/RHSA-2020:5645
USN-4671-1 https://usn.ubuntu.com/4671-1/
USN-4701-1 https://usn.ubuntu.com/4701-1/
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-2020-26974.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:M/Au:N/C:P/I:P/A:P Found at https://nvd.nist.gov/vuln/detail/CVE-2020-26974
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-2020-26974
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 0.66449
EPSS Score 0.00535
Published At Aug. 6, 2025, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2025-07-31T08:09:38.954776+00:00 Mozilla Importer Import https://github.com/mozilla/foundation-security-advisories/blob/master/announce/2020/mfsa2020-54.yml 37.0.0