Background exploitation KEV catalog No authentication

CVE-2020-6820

Mozilla Firefox And Thunderbird Use-After-Free Vulnerability

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…

CheckOps priority index

5.3/10 Patch within 7 days

Severity8.1

Probability0.7

Exploitation3/5

Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.

EPSS · today 7.1% higher than 94.2% of CVEs

CVSS 3.1 8.1 AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:

Exploited for 1,826 days 03 Nov 2021

CISA due date 03 May 2022 for US federal agencies

Exploitation probability EPSS · FIRST

EPSS probability (%)Percentile among all CVEs

Exploitation signals 3 / 5

KEV catalog (CISA)03 Nov 2021
Exploited in EUVD (ENISA)03 Nov 2021
Used by ransomwareno
EPSS above 10 %7.1%
No account, over the networkyes

What to do

Fix

Apply the vendor’s fix as soon as it is available.

CISA guidance: Apply updates per vendor instructions.

Meanwhile

Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.

Manufacturers (CRA)

Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained

Description ENISA EUVD

Affected products

Firefox ESRThunderbirdFirefoxFirefox and Thunderbird

Affected versions

unspecified <68.6.1
unspecified <68.7.0
unspecified <74.0.1

Weaknesses (CWE)

CWE-362

Open source packages OSV

Affected libraries according to OSV, with fixed versions.

Timeline

24 Apr 2020
Published
03 Nov 2021
Exploitation reported (ENISA)
03 Nov 2021
Added to the KEV catalog
03 May 2022
CISA remediation due date

References

Other exploited vulnerabilities from the same vendor

CVE-2010-3765Mozilla Multiple Products Remote Code Execution Vulnerability
8.8 · Background exploitation
CVE-2024-9680Mozilla Firefox Use-After-Free Vulnerability
7.6 · Background exploitation
CVE-2016-9079Mozilla Firefox, Firefox ESR, and Thunderbird Use-After-Free Vulnerability
8.0 · Background exploitation
CVE-2015-4495Mozilla Firefox Security Feature Bypass Vulnerability
8.0 · Background exploitation
CVE-2019-11708Mozilla Firefox and Thunderbird Sandbox Escape Vulnerability
8.1 · Background exploitation
CVE-2019-11707Mozilla Firefox and Thunderbird Type Confusion Vulnerability
7.1 · Background exploitation