CVE-2020-6820
Race Condition: Is CVE-2020-6820 real, exploitable, or a false positive? Here's the community verdict.
Community verdict: No field verdicts yet. Be the first practitioner to weigh in.
signals
public sources
Confirmed exploited in the wild. Patch this first, regardless of the base score.
cisa ssvc
CISA Vulnrichment · assessed
CISA decision, by how critical the affected system is to you:
- low impact → Track
- medium impact → Attend
- high impact → Act
Track: normal patch cycle · Track*: watch closely · Attend: patch sooner · Act: patch now. About SSVC ↗
baseline read
auto · not a community verdict
Real — exploited in the wild
CISA confirms active exploitation. Treat scanner hits as true positives unless your specific version or config is unaffected.
Based on CISA KEV
Confirm or dispute →CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
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.
References
Published · Added to CISA KEV (558 days after publication)
Embed this verdict
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timeline
- CISA SSVC assessment · exploitation: active
- Added to CISA KEV · confirmed exploited in the wild
- Published by NVD
- Added to VulnCheck KEV · reported exploited in the wild
Score and exploit changes tracked since .
Community ground truth
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In your experience, is this finding real and exploitable?
awaiting field verdictsCurated baseline: TruePositive's read from public sources is Real & exploitable — a starting point, not a community verdict.
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Field notes & remediation
Verdicts are the quick signal. Notes are the evidence and fixes behind them.
- 0
Mozilla Firefox And Thunderbird Use-After-Free Vulnerability — 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. Listed in the CISA KEV catalog (added 2021-11-03) — confirmed exploited in the wild, not theoretical. FIRST EPSS puts the chance of exploitation in the next 30 days at ~7%. Treat it as real and prioritize remediation over triage.
- 0
Required action for Mozilla Firefox and Thunderbird: Apply updates per vendor instructions. CISA set a federal remediation due date of 2022-05-03. After patching, verify the vulnerable path is no longer reachable before closing the finding.
Add a field note or remediationoptional
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