Known exploited vulnerability
CVE-2020-6820
The short answer
CVE-2020-6820 affects Mozilla Thunderbird and is rated high (CVSS 8.1). CISA added it to the Known Exploited Vulnerabilities catalog on 2021-11-03: attackers are using it, so patch it first.
What it is
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.
Weakness: CWE-362.
Severity
8.1 high
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Exploited (CISA KEV)
Yes, since Nov 3, 2021
Federal due date May 3, 2022
EPSS, next 30 days
7.1%
Higher than 94% of scored CVEs
How it can be exploited
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
What CISA says to do
Apply updates per vendor instructions.
Affected products
Thunderbird, Firefox, Firefox ESR. NVD's record lists the exact affected versions.
References
- bugzilla.mozilla.org/show_bug.cgi?id=1626728 Issue TrackingPermissions Required
- usn.ubuntu.com/4335-1/ Third Party Advisory
- www.mozilla.org/security/advisories/mfsa2020-11/ Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2020-14/ Vendor Advisory
- bugzilla.mozilla.org/show_bug.cgi?id=1626728 Issue TrackingPermissions Required
- usn.ubuntu.com/4335-1/ Third Party Advisory
- www.mozilla.org/security/advisories/mfsa2020-11/ Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2020-14/ Vendor Advisory
- www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-6820 US Government Resource
Questions
Is CVE-2020-6820 being exploited?
Yes. CISA added CVE-2020-6820 to its Known Exploited Vulnerabilities catalog on 2021-11-03, with a federal remediation due date of 2022-05-03.
How do I fix CVE-2020-6820?
CISA's required action: Apply updates per vendor instructions.
From NVD, CISA KEV, FIRST EPSS and OSV.dev, checked . Status on NVD: Analyzed. The description is NVD's text, quoted as published.
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