What’s Vulnerable › Vulnerabilities

CVE-2020-6821

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-04-24 · updated 2026-06-17
• Weakness: CWE-908

Description

When reading from areas partially or fully outside the source resource with WebGL's <code>copyTexSubImage</code> method, the specification requires the returned values be zero. Previously, this memory was uninitialized, leading to potentially sensitive data disclosure. This vulnerability affects Thunderbird < 68.7.0, Firefox ESR < 68.7, and Firefox < 75.

Affected products

• Mozilla Firefox: before 75.0 — fixed in 75.0
• Mozilla Firefox ESR: before 68.7.0 — fixed in 68.7.0
• Mozilla Thunderbird: before 68.7.0 — fixed in 68.7.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 75.0; Mozilla Firefox ESR 68.7.0; Mozilla Thunderbird 68.7.0. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1625404
• https://usn.ubuntu.com/4335-1/
• https://www.mozilla.org/security/advisories/mfsa2020-12/
• https://www.mozilla.org/security/advisories/mfsa2020-13/
• https://www.mozilla.org/security/advisories/mfsa2020-14/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1625404
• https://usn.ubuntu.com/4335-1/
• https://www.mozilla.org/security/advisories/mfsa2020-12/
• https://www.mozilla.org/security/advisories/mfsa2020-13/
• https://www.mozilla.org/security/advisories/mfsa2020-14/

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