CISA KEV · Known exploitedHigh

CVE-2020-6819

Mozilla Firefox and Thunderbird

Under certain conditions, when running the nsDocShell destructor, 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.

CVSS
8.1
EPSS
2.98%
85.9% percentile
CISA KEV
Listed
Published
2020.04.25
PRIORITY ASSESSMENT

Immediate review

CISA has listed this vulnerability in the Known Exploited Vulnerabilities catalog.

Known exploitationConfirmed by CISA KEV
Exploit probability2.98%
Technical severityCVSS 8.1

Vulnerability overview

Under certain conditions, when running the nsDocShell destructor, 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.

Affected product and versions

Product
Mozilla Firefox and Thunderbird
Affected versions
unspecified, < 68.6.1, < 74.0.1, < 68.7.0
Fixed versions
68.6.1, 74.0.1, 68.7.0

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
CISA required action

Apply updates per vendor instructions.

Due date: 2022.05.03
  1. 1
    Identify

    Confirm that Mozilla Firefox and Thunderbird and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE
CWE-362, CWE-416
KEV added
2021.11.03
Ransomware use
미확인
CVE-2020-6819 — Mozilla Firefox and Thunderbird | SECUFOCUS NOW