Sandbox escape via unchecked WebGPU binding index
Published Nov 11, 2025 · Updated Apr 13, 2026
Improper boundary checking in Mozilla Firefox and Thunderbird before 145 allows remote attackers to write outside bounds in a privileged process. Derived bind group layout creation skips the maximum-bindings check, so a huge WGSL binding index drives an out-of-bounds write through an unchecked offset calculation. Malicious WebGPU shader input is required; the write can crash the process or escape the content sandbox, while Thunderbird disables scripting during normal email reading.
Summary
What happened
Improper boundary checking in Mozilla Firefox and Thunderbird before 145 allows remote attackers to write outside bounds in a privileged process. Derived bind group layout creation skips the maximum-bindings check, so a huge WGSL binding index drives an out-of-bounds write through an unchecked offset calculation. Malicious WebGPU shader input is required; the write can crash the process or escape the content sandbox, while Thunderbird disables scripting during normal email reading.
The record
- CVE
- CVE-2025-13021
- Published
- Nov 11, 2025
- Updated
- Apr 13, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-703, T1068
- Attack vector
- Unavailable
- Privileges
- Unavailable
Timeline
How it unfolded
- Nov 11, 2025CVE publishedPublication date reported by the CVE source.
- Apr 13, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
What conditions does exploitation require?
What is affected?
Affected products and versions are unavailable in this record.
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- WebGPU high-binding-index crash test caseproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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