How severe is CVE-2020-6815?

CVE-2020-6815 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2020-6815 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (68th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-6815?

CVE-2020-6815 affects Mozilla Firefox. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-6815?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2020-6815 published?

CVE-2020-6815 was published on 2020-03-25 and last updated on 2026-06-17.

CVE-2020-6815

CVE-2020-6815 is a critical-severity vulnerability in Mozilla Firefox with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-787.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 1% (68th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-787
Affected product: Mozilla Firefox
Published: 2020-03-25
Last modified: 2026-06-17

Description

Mozilla developers reported memory safety and script safety bugs present in Firefox 73. Some of these bugs showed evidence of memory corruption or escalation of privilege and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 74.

Frequently asked questions

What is CVE-2020-6815?: Mozilla developers reported memory safety and script safety bugs present in Firefox 73. Some of these bugs showed evidence of memory corruption or escalation of privilege and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 74.
How severe is CVE-2020-6815?: CVE-2020-6815 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2020-6815 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (68th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-6815?: CVE-2020-6815 affects Mozilla Firefox. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-6815?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2020-6815 published?: CVE-2020-6815 was published on 2020-03-25 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*

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