CVE-2020-6819
Publication date 3 April 2020
Last updated 25 August 2025
Ubuntu priority
Cvss 3 Severity Score
Description
Under certain conditions, when running the nsDocShell destructor, 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.
Status
| Package | Ubuntu Release | Status | 
|---|---|---|
| firefox | 20.04 LTS focal | 
                              
                               
                                Fixed 75.0+build3-0ubuntu1 
                                
                               
                             |      
                          
                            
                          
                        
                      
| 18.04 LTS bionic | 
                              
                               
                                Fixed 74.0.1+build1-0ubuntu0.18.04.1 
                                
                               
                             |      
                          
                            
                          
                        
                      |
| 16.04 LTS xenial | 
                              
                               
                                Fixed 74.0.1+build1-0ubuntu0.16.04.1 
                                
                               
                             |      
                          
                            
                          
                        
                      |
| 14.04 LTS trusty | Not in release | |
| thunderbird | 20.04 LTS focal | 
                              
                               
                                Fixed 1:68.7.0+build1-0ubuntu1 
                                
                               
                             |      
                          
                            
                          
                        
                      
| 18.04 LTS bionic | 
                              
                               
                                Fixed 1:68.7.0+build1-0ubuntu0.18.04.1 
                                
                               
                             |      
                          
                            
                          
                        
                      |
| 16.04 LTS xenial | 
                              
                               
                                Fixed 1:68.7.0+build1-0ubuntu0.16.04.2 
                                
                               
                             |      
                          
                            
                          
                        
                      |
| 14.04 LTS trusty | Not in release | 
Notes
Severity score breakdown
| Parameter | Value | 
|---|---|
| Base score | 
                      
                      
                         | 
                  
| Attack vector | Network | 
| Attack complexity | High | 
| Privileges required | None | 
| User interaction | None | 
| Scope | Unchanged | 
| Confidentiality | High | 
| Integrity impact | High | 
| Availability impact | High | 
| Vector | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H | 
References
Related Ubuntu Security Notices (USN)
- USN-4328-1
 - Thunderbird vulnerabilities
 - 13 April 2020
 - USN-4335-1
 - Thunderbird vulnerabilities
 - 21 April 2020
 - USN-4317-1
 - Firefox vulnerabilities
 - 4 April 2020