// For flags

CVE-2020-6820

Mozilla Firefox And Thunderbird Use-After-Free Vulnerability

Severity Score

8.1
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

Yes
*KEV

Decision

-
*SSVC
Descriptions

Under certain conditions, when handling a ReadableStream, a race condition can cause a use-after-free. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Thunderbird < 68.7.0, Firefox < 74.0.1, and Firefox ESR < 68.6.1.

Bajo determinadas condiciones, cuando se maneja un ReadableStream, una condiciĆ³n de carrera puede causar un uso de la memoria previamente liberada. Somos conscientes de los ataques dirigidos "in the wild" que abusan de este fallo. Esta vulnerabilidad afecta a Thunderbird versiones anteriores a 68.7.0, Firefox versiones anteriores a 74.0.1 y Firefox ESR versiones anteriores a 68.6.1.

A flaw was found in Mozilla's Firefox. A race condition can occur when handling a ReadableStream causing a use-after-free memory issue. The highest threat from this vulnerability are to data confidentiality and integrity as well as system availability.

Mozilla Firefox and Thunderbird contain a race condition vulnerability when handling a ReadableStream under certain conditions. The race condition creates a use-after-free vulnerability, causing unspecified impacts.

*Credits: N/A
CVSS Scores
Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Attack Vector
Network
Attack Complexity
Medium
Authentication
None
Confidentiality
Partial
Integrity
Partial
Availability
Partial
* Common Vulnerability Scoring System
SSVC
  • Decision:-
Exploitation
-
Automatable
-
Tech. Impact
-
* Organization's Worst-case Scenario
Timeline
  • 2020-01-10 CVE Reserved
  • 2020-04-06 CVE Published
  • 2021-11-03 Exploited in Wild
  • 2022-05-03 KEV Due Date
  • 2024-02-27 EPSS Updated
  • 2024-08-04 CVE Updated
  • ---------- First Exploit
CWE
  • CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
  • CWE-416: Use After Free
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Mozilla
Search vendor "Mozilla"
Firefox
Search vendor "Mozilla" for product "Firefox"
< 74.0.1
Search vendor "Mozilla" for product "Firefox" and version " < 74.0.1"
-
Affected
Mozilla
Search vendor "Mozilla"
Firefox Esr
Search vendor "Mozilla" for product "Firefox Esr"
< 68.6.1
Search vendor "Mozilla" for product "Firefox Esr" and version " < 68.6.1"
-
Affected
Mozilla
Search vendor "Mozilla"
Thunderbird
Search vendor "Mozilla" for product "Thunderbird"
< 68.7.0
Search vendor "Mozilla" for product "Thunderbird" and version " < 68.7.0"
-
Affected