CVE-2020-6820
Mozilla Firefox and Thunderbird: Use-After-Free
As of , CVE-2020-6820 in Mozilla Firefox and Thunderbird is on CISA's list of exploited vulnerabilities: CISA listed it on . Our patch-first group: Patch soon.
- Exploited
- Yes: CISA listed it on 3 November 2021
- US federal deadline
- 3 May 2022181 days after CISA listed it. US federal civilian agencies must fix it by then.
- Used in ransomware campaigns
- Not known to CISA
- EPSS score
- 0.07Higher than 94% of the CVEs EPSS scores. EPSS estimates the chance of exploitation activity in the next 30 days.
- EPSS when listed
- Not availableCISA listed it before 4 February 2022, where the EPSS files we read begin.
- Public exploit
- None foundNeither Metasploit nor Exploit-DB lists one.
- Fix
- No vendor link in CISA's entry
What CISA says to do
Apply updates per vendor instructions.
CISA's required action
What the flaw is
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.
CISA's description
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.
The CVE record's description, from mozilla
- CVE published
- 24 April 2020
- Assigned by
- mozilla
- CVSS
- 8.1 High (CVSS 3.1, from CISA-ADP)
- CWE-362
- Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
- CISA SSVC, exploitation
- active
- CISA SSVC, automatable
- no
- CISA SSVC, technical impact
- total
Timeline
- The CVE record was published.
- CISA added it to its list of exploited vulnerabilities.
- The US federal deadline to fix it.
Firefox and Thunderbird: other exploited entries
| Vulnerability | Product | Our group | Listed | Deadline | EPSS |
|---|---|---|---|---|---|
| CVE-2013-1690Denial-of-Service | Mozilla Firefox and Thunderbird | Patch this weekMetasploit module; EPSS 0.69; verified Exploit-DB entry | 0.69 | ||
| CVE-2019-11708Sandbox Escape | Mozilla Firefox and Thunderbird | Patch this weekEPSS 0.56 | 0.56 | ||
| CVE-2019-11707Type Confusion | Mozilla Firefox and Thunderbird | Patch soonVerified Exploit-DB entry | 0.38 | ||
| CVE-2019-17026Type Confusion | Mozilla Firefox and Thunderbird | Patch soon | 0.46 | ||
| CVE-2020-6819Use-After-Free | Mozilla Firefox and Thunderbird | Patch soon | 0.03 |
Read further
- CVE recordcve.org
- NVD entrynvd.nist.gov
- CISA's catalogcisa.gov
- EPSS for this CVEapi.first.org