CVE-2020-26959
HIGH
8.8
CVSS Score
Published: December 9, 2020 at 12:22 AM UTC
Updated: June 17, 2026 at 03:08 AM UTC
3 products affected across 1 vendorFirefoxThunderbirdFirefox ESR
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Severity
HIGH8.8
Exploit prediction
EPSS 1%
Description
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. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.
Affected
Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.
v < 83
Affected range stops below 83, so it looks safe — our inference, not a vendor statement
Affected range stops below 83.0, so it looks safe — our inference, not a vendor statement
v < 78.5
Affected range stops below 78.5, so it looks safe — our inference, not a vendor statement
v < 78.5
Affected range stops below 78.5, 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_MISCIssue TrackingPermissions RequiredVendor Advisory
Source: [email protected]
https://bugzilla.mozilla.org/show_bug.cgi?id=1669466x_refsource_CONFIRMVendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2020-50/x_refsource_CONFIRMVendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2020-51/x_refsource_CONFIRMVendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2020-52/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-416
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