CVE-2020-6820 : Under certain conditions, when handling a ReadableStream, a race condition can c

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.

Published 2020-04-24 16:15:13

Updated 2022-07-12 17:42:04

Source Mozilla Corporation

View at NVD, CVE.org

Vulnerability category: Memory Corruption

Products affected by CVE-2020-6820

Mozilla » Firefox
Versions before (<) 74.0.1
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
Matching versions
Mozilla » Thunderbird
Versions before (<) 68.7.0
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
Matching versions
Mozilla » Firefox Esr
Versions before (<) 68.6.1
cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*
Matching versions

CVE-2020-6820 is in the CISA Known Exploited Vulnerabilities Catalog

CISA vulnerability name:

Mozilla Firefox And Thunderbird Use-After-Free Vulnerability

CISA required action:

Apply updates per vendor instructions.

CISA description:

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.

Notes:

https://nvd.nist.gov/vuln/detail/CVE-2020-6820

Added on 2021-11-03 Action due date 2022-05-03

Exploit prediction scoring system (EPSS) score for CVE-2020-6820

EPSS FAQ

1.07%

Probability of exploitation activity in the next 30 days EPSS Score History

~ 84 %

Percentile, the proportion of vulnerabilities that are scored at or less

CVSS scores for CVE-2020-6820

Base Score	Base Severity	CVSS Vector	Exploitability Score	Impact Score	Score Source
6.8	MEDIUM	AV:N/AC:M/Au:N/C:P/I:P/A:P	8.6	6.4	NIST
Access Vector: Network Access Complexity: Medium Authentication: None Confidentiality Impact: Partial Integrity Impact: Partial Availability Impact: Partial
8.1	HIGH	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H	2.2	5.9	NIST
Attack Vector: Network Attack Complexity: High Privileges Required: None User Interaction: None Scope: Unchanged Confidentiality: High Integrity: High Availability: High

CWE ids for CVE-2020-6820

CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.

Assigned by: nvd@nist.gov (Primary)

References for CVE-2020-6820

https://www.mozilla.org/security/advisories/mfsa2020-11/

Security Vulnerabilities fixed in Firefox 74.0.1 and Firefox ESR 68.6.1 — Mozilla
Vendor Advisory

CVEs referencing this url
https://bugzilla.mozilla.org/show_bug.cgi?id=1626728

Access Denied
Issue Tracking;Permissions Required
https://usn.ubuntu.com/4335-1/

USN-4335-1: Thunderbird vulnerabilities | Ubuntu security notices
Third Party Advisory

CVEs referencing this url
https://www.mozilla.org/security/advisories/mfsa2020-14/

Security Vulnerabilities fixed in Thunderbird 68.7.0 — Mozilla
Vendor Advisory

CVEs referencing this url