Remote code execution in Mozilla Firefox and Firefox ESR
| Risk | Critical |
| Patch available | YES |
| Number of vulnerabilities | 2 |
| CVE-ID | CVE-2020-6819 CVE-2020-6820 |
| CWE-ID | CWE-416 |
| Exploitation vector | Network |
| Public exploit |
Vulnerability #1 is being exploited in the wild. Vulnerability #2 is being exploited in the wild. |
| Vulnerable software Subscribe |
Mozilla Firefox Client/Desktop applications / Web browsers Firefox ESR Client/Desktop applications / Web browsers |
| Vendor | Mozilla |
Security Bulletin
This security bulletin contains information about 2 vulnerabilities.
1) Use-after-free
EUVDB-ID: #VU26573
Risk: Critical
CVSSv3.1: 8.4 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C]
CVE-ID: CVE-2020-6819
CWE-ID:
CWE-416 - Use After Free
Exploit availability: No
DescriptionThe vulnerability allows a remote attacker to compromise vulnerable system.
The vulnerability exists due to a use-after-free error caused by a race condition running the nsDocShell destructor. A remote attacker can create a specially crafted website, trick the victim into visiting it, trigger a use-after-free error and execute arbitrary code on the system.
Successful exploitation of the vulnerability may allow an attacker to compromise vulnerable system.
Note, this vulnerability is being actively exploited in the wild in targeted attacks.
Install updates from vendor's website.
Vulnerable software versionsMozilla Firefox: 60.0 - 74.0
Firefox ESR: 60.0 - 68.6.0
External linkshttp://www.mozilla.org/en-US/security/advisories/mfsa2020-11/
http://bugzilla.mozilla.org/show_bug.cgi?id=1620818
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.
How the attacker can exploit this vulnerability?
The attacker would have to trick the victim to visit a specially crafted website.
Is there known malware, which exploits this vulnerability?
Yes. This vulnerability is being exploited in the wild.
2) Use-after-free
EUVDB-ID: #VU26574
Risk: Critical
CVSSv3.1: 8.4 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C]
CVE-ID: CVE-2020-6820
CWE-ID:
CWE-416 - Use After Free
Exploit availability: No
DescriptionThe vulnerability allows a remote attacker to compromise vulnerable system.
The vulnerability exists due to a use-after-free error caused by a race condition handling ReadableStream. A remote attacker can create a specially crafted website, trick the victim into visiting it, trigger a use-after-free error and execute arbitrary code on the system.
Successful exploitation of the vulnerability may allow an attacker to compromise vulnerable system.
Note, this vulnerability is being actively exploited in the wild in targeted attacks.
Install updates from vendor's website.
Vulnerable software versionsMozilla Firefox: 60.0 - 74.0
Firefox ESR: 60.0 - 68.6.0
External linkshttp://www.mozilla.org/en-US/security/advisories/mfsa2020-11/
http://bugzilla.mozilla.org/show_bug.cgi?id=1626728
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.
How the attacker can exploit this vulnerability?
The attacker would have to trick the victim to visit a specially crafted website.
Is there known malware, which exploits this vulnerability?
Yes. This vulnerability is being exploited in the wild.
