HighFix available
firefox-esr, thunderbird — security advisory
When reading from areas partially or fully outside the source resource with WebGL's copyTexSubImage 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.
- Products
- firefox-esr, thunderbird
- Affected versions
- Not specified
- Fixed versions
- 1:68.7.0-1, 68.7.0esr-1
- CVEs
- CVE-2020-6821
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 14:09 UTC · Revision 1
Source evidence
When reading from areas partially or fully outside the source resource with WebGL's copyTexSubImage 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.
osv:DEBIAN-CVE-2020-6821
firefox-esr
Fixed versions: 68.7.0esr-1
firefox-esr
Fixed versions: 68.7.0esr-1
firefox-esr
Fixed versions: 68.7.0esr-1
thunderbird
Fixed versions: 1:68.7.0-1
thunderbird
Fixed versions: 1:68.7.0-1
thunderbird
Fixed versions: 1:68.7.0-1
Complete source record
{
"id": "073054767481473d9bcb0e2c30d0ff01f3a518537e255dd0c449f042107ba37b",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2020-6821",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2020-6821",
"summary": "When reading from areas partially or fully outside the source resource with WebGL's copyTexSubImage 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.",
"evidence": "osv:DEBIAN-CVE-2020-6821",
"products": [
{
"name": {
"value": "firefox-esr",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "68.7.0esr-1",
"evidence": "/affected/0/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "firefox-esr",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "68.7.0esr-1",
"evidence": "/affected/1/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "firefox-esr",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "68.7.0esr-1",
"evidence": "/affected/2/ranges"
}
],
"affected_versions": []
},
{
"name": {
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"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "1:68.7.0-1",
"evidence": "/affected/3/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "thunderbird",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "1:68.7.0-1",
"evidence": "/affected/4/ranges"
}
],
"affected_versions": []
},
{
"name": {
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"evidence": "/affected/5/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
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"evidence": "/affected/5/ranges"
}
],
"affected_versions": []
}
],
"severity": "high",
"structured": {
"id": "DEBIAN-CVE-2020-6821",
"aliases": [
"DEBIAN-CVE-2020-6821"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "68.7.0esr-1"
}
]
}
],
"package": {
"name": "firefox-esr",
"purl": "pkg:deb/debian/firefox-esr?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2020-6821.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
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"events": [
{
"introduced": "0"
},
{
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],
"package": {
"name": "firefox-esr",
"purl": "pkg:deb/debian/firefox-esr?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2020-6821.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
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{
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],
"package": {
"name": "firefox-esr",
"purl": "pkg:deb/debian/firefox-esr?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2020-6821.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
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],
"package": {
"name": "thunderbird",
"purl": "pkg:deb/debian/thunderbird?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2020-6821.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
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{
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}
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}
],
"package": {
"name": "thunderbird",
"purl": "pkg:deb/debian/thunderbird?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2020-6821.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "1:68.7.0-1"
}
]
}
],
"package": {
"name": "thunderbird",
"purl": "pkg:deb/debian/thunderbird?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2020-6821.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-26T12:02:51.687444185Z",
"provider": "osv",
"upstream": [
"CVE-2020-6821"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2020-6821"
]
},
"related_cves": [
{
"value": "CVE-2020-6821",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 453216,
"published_at": "2020-04-24T16:15:13.51+00:00"
}