Vulnerability in Mozilla Firefox
CVE-2020-6820
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 F…
Vulnerability class: Race Condition
EPSS: 0.063 (92.8th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Mozilla Firefox — versions unspecified
- Mozilla Firefox Esr — versions unspecified
- Mozilla Thunderbird — versions unspecified
Weakness classification (CWE)
CISA KEV (Known Exploited Vulnerabilities)
This CVE is on the CISA KEV catalog, added on . CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.
BOD 22-01 due date: .
Required action: Apply updates per vendor instructions.
Public proof-of-concept exploits
References
- security@mozilla.org (x_refsource_MISC, Vendor Advisory)
- security@mozilla.org (x_refsource_MISC, Vendor Advisory)
- security@mozilla.org (Permissions Required, x_refsource_MISC, Issue Tracking)
- security@mozilla.org (x_refsource_UBUNTU, vendor-advisory, Third Party Advisory)
- 134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource)
Frequently asked questions
- What is CVE-2020-6820?
- CVE-2020-6820 is a high-severity vulnerability in Mozilla Firefox, classified under Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition). CVSS score: 8.1/10. Published 2020-04-24.
- How severe is CVE-2020-6820?
- High severity. CVSS v3 base score is 8.1 out of 10.
- Is CVE-2020-6820 known to be exploited?
- Yes. CVE-2020-6820 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), indicating it is being actively exploited. 2 public proof-of-concept repositories are indexed.