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CVE-2026-74946

Information disclosure due to incorrect boundary conditions in the Graphics: CanvasWebGL component

HIGH
8.8
CVSS Score
Published: August 18, 2026 at 12:23 PM UTC
Updated: October 28, 2026 at 05:18 PM UTC
2 products affected across 1 vendorFirefoxThunderbird

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Severity
HIGH8.8
Exploit prediction
EPSS 0.5%
SSVC
No known exploit

Description

Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, and Firefox ESR 153.1.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Firefox· Mozilla
95%
v < 115.39.0116.0 ≤ v < 140.14.0141.0 ≤ v < 153.1.0
Vendor states this is fixed in 115.39 (unaffected)
Affected range stops below 115.39.0, so it looks safe — our inference, not a vendor statement
Vendor states this is fixed in 140.14 (unaffected)
Affected range stops below 140.14.0, so it looks safe — our inference, not a vendor statement
Vendor states this is fixed in 153.1 (unaffected)
Affected range stops below 153.1.0, so it looks safe — our inference, not a vendor statement
Vendor states this is fixed in 154 (unaffected)
Thunderbird· Mozilla
95%
v < 140.14.0141.0 ≤ v < 153.1.0
Vendor states this is fixed in 140.14 (unaffected)
Affected range stops below 140.14.0, so it looks safe — our inference, not a vendor statement
Vendor states this is fixed in 153.1 (unaffected)
Affected range stops below 153.1.0, so it looks safe — our inference, not a vendor statement
Vendor states this is fixed in 154 (unaffected)

References (8)

Permissions Required
Source: cverecord
https://bugzilla.mozilla.org/show_bug.cgi?id=2059997
Vendor Advisory
Source: cverecord
https://www.mozilla.org/security/advisories/mfsa2026-74/
Vendor Advisory
Source: cverecord
https://www.mozilla.org/security/advisories/mfsa2026-75/
Vendor Advisory
Source: cverecord
https://www.mozilla.org/security/advisories/mfsa2026-76/
Vendor Advisory
Source: cverecord
https://www.mozilla.org/security/advisories/mfsa2026-77/
Vendor Advisory
Source: cverecord
https://www.mozilla.org/security/advisories/mfsa2026-78/
Vendor Advisory
Source: cverecord
https://www.mozilla.org/security/advisories/mfsa2026-79/
Vendor Advisory
Source: cverecord
https://www.mozilla.org/security/advisories/mfsa2026-80/

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.8HIGHCISA-ADP
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-119

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