Is CVE-2020-6820 actively exploited?

Yes. CVE-2020-6820 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, which means exploitation in the wild has been confirmed.

Can CVE-2020-6820 be exploited remotely?

The attack vector of CVE-2020-6820 has not been classified yet.

What is the CVSS score of CVE-2020-6820?

CVE-2020-6820 has not received a CVSS score yet.

HOME VULNERABILITIESCVE-2020-6820

HIGHCISA KEVIN THE WILD

CVE-2020-6820

Published: November 3, 2021

EPSS:5.00%probability of exploitation in 30 daysPercentile:89.5th

Official 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.

NVD Source

CISA KEV Advisory

Mozilla Firefox And Thunderbird Use-After-Free Vulnerability

Added to KEV: 2021-11-03Federal patch deadline: 2022-05-03

Required Action (CISA)

Apply updates per vendor instructions.

Risk Analysis

Mozilla Firefox and Thunderbird contain a race condition vulnerability when handling ReadableStream objects, leading to a use-after-free condition with unspecified impacts. Its presence in the KEV catalog indicates confirmed exploitation, making it an urgent concern for users.

This vulnerability is actively being exploited in the wild. Given it affects web browsers and email clients, exploitation is likely remote through crafted content.

Recommended Action

Users should update Mozilla Firefox and Thunderbird to the latest versions to mitigate this use-after-free vulnerability.

Generated by the CTIWATCH analysis pipeline from this CVE's metadata (CVSS, EPSS, KEV status, exploit intelligence). Verify against vendor advisories before acting.

Technical Analysis

CVE-2020-6820 requires local access, meaning attackers must already have a foothold on the target system.

Exploitation requires some privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

CISA has added CVE-2020-6820 to the Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. U.S. federal agencies are required to patch this within the mandated timeframe, and all organizations should treat remediation as urgent.