CVE-2020-6820 on CISA KEV

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.

01What CISA says about this 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 Firefox ESR < 68.6.1.

02Required action — verbatim from CISA

Apply updates per vendor instructions.

03Notes & references

• www.mozilla.org — https://www.mozilla.org/security/advisories/mfsa2020-14/
• www.mozilla.org — https://www.mozilla.org/security/advisories/mfsa2020-11/
• bugzilla.mozilla.org — https://bugzilla.mozilla.org/show_bug.cgi?id=1626728
• usn.ubuntu.com — https://usn.ubuntu.com/4335-1/

04SARA's analyst layer — why this matters

This vulnerability is currently on the CISA KEV list, which CISA only adds CVEs to when there is reliable evidence of active exploitation in the wild. For federal civilian agencies, BOD 22-01 requires remediation by the due date above. For everyone else, KEV is the strongest "patch immediately" signal you can get from public threat intel.

05Affected products (summary)

Vendor	Product	Versions
Mozilla	Thunderbird	unspecified
Mozilla	Firefox	unspecified
Mozilla	Firefox ESR	unspecified

06Detection

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