CVE-2020-26974
HIGH
8.8
CVSS Score
Published: January 7, 2021 at 01:52 PM UTC
Updated: June 17, 2026 at 03:08 AM UTC
3 products affected across 1 vendorFirefoxThunderbirdFirefox ESR
Using Firefox by Mozilla?
Get instant alerts when new vulnerabilities affect Firefox - before attackers find them.
Real-time alertsTrack your software stackFree plan available
Severity
HIGH8.8
Exploit prediction
EPSS 2%
Description
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. This vulnerability affects Firefox < 84, Thunderbird < 78.6, and Firefox ESR < 78.6.
Affected
Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.
v < 84
Affected range stops below 84, so it looks safe — our inference, not a vendor statement
Affected range stops below 84.0, so it looks safe — our inference, not a vendor statement
v < 78.6
Affected range stops below 78.6, so it looks safe — our inference, not a vendor statement
Affected range stops below 78.6.0, so it looks safe — our inference, not a vendor statement
v < 78.6
Affected range stops below 78.6, so it looks safe — our inference, not a vendor statement
Affected range stops below 78.6.0, so it looks safe — our inference, not a vendor statement
Remediation
No guide yetNo remediation guidance has been written for this CVE yet. What the record does show:
References (4)
x_refsource_MISCPermissions Required
Source: [email protected]
https://bugzilla.mozilla.org/show_bug.cgi?id=1681022x_refsource_MISCVendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2020-54/x_refsource_MISCVendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2020-55/x_refsource_MISCVendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2020-56/CVSS
- Attack Vector
- NETWORK
- Complexity
- LOW
- Privileges
- NONE
- User Interaction
- REQUIRED
- Scope
- UNCHANGED
- Confidentiality
- HIGH
- Integrity
- HIGH
- Availability
- HIGH
Vector?
Quick Info
StatusMODIFIED
CWE
CWE-787
Get alerted
Stop reading CVE feeds looking for your own stack
Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.
Free plan, no card