Sandbox escape via unchecked Canvas2D buffer queue
Published Sep 16, 2025 · Updated Sep 16, 2025
Sandbox escape in Mozilla Firefox and Thunderbird before 143, including ESR before 140.3, allows attackers to break content isolation. CanvasTranslator::NextBuffer processes a RecordedDropBuffer event by reading and popping mCanvasShmems without checking whether the queue is empty, causing out-of-bounds heap reads and writes. Exploitation requires control of a sandboxed content process; Thunderbird disables scripting in mail, so browser-like contexts carry its exposure.
Summary
What happened
Sandbox escape in Mozilla Firefox and Thunderbird before 143, including ESR before 140.3, allows attackers to break content isolation. CanvasTranslator::NextBuffer processes a RecordedDropBuffer event by reading and popping mCanvasShmems without checking whether the queue is empty, causing out-of-bounds heap reads and writes. Exploitation requires control of a sandboxed content process; Thunderbird disables scripting in mail, so browser-like contexts carry its exposure.
The record
- CVE
- CVE-2025-10528
- Published
- Sep 16, 2025
- Updated
- Sep 16, 2025
- Vendor
- Mozilla
- Product
- Firefox
- Classifications
- CWE-693, T1203
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 16, 2025CVE publishedPublication date reported by the CVE source.
- Sep 16, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=unspecified <143
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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