CVE-2020-26950
HIGH
8.8
CVSS Score
Published: December 9, 2020 at 12:19 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 42%
Description
In certain circumstances, the MCallGetProperty opcode can be emitted with unmet assumptions resulting in an exploitable use-after-free condition. This vulnerability affects Firefox < 82.0.3, Firefox ESR < 78.4.1, and Thunderbird < 78.4.2.
Affected
Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.
v < 82.0.3
Affected range stops below 82.0.3, so it looks safe — our inference, not a vendor statement
v < 78.4.1
Affected range stops below 78.4.1, so it looks safe — our inference, not a vendor statement
v < 78.4.2
Affected range stops below 78.4.2, 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:
Patch and advisory references
References (3)
x_refsource_MISCExploitThird Party AdvisoryVDB Entry
Source: [email protected]
http://packetstormsecurity.com/files/166175/Firefox-MCallGetProperty-Write-Side-Effects-Use-After-Free.htmlx_refsource_MISCExploitIssue TrackingVendor Advisory
Source: [email protected]
https://bugzilla.mozilla.org/show_bug.cgi?id=1675905x_refsource_CONFIRMVendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2020-49/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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