Mozilla Sandbox Escape Vulnerability - 20260819001¶
Overview¶
The WASOC has observed updates from Mozilla relating to a maximum severity vulnerability affecting their Firefox and Thunderbird products. An unauthenticated attacker with access to a system running the affected browser can break out of the sandbox environment and execute code outside the sandbox restrictions.
What is vulnerable?¶
| Product(s) Affected | Version(s) | CVE | CVSS | Severity |
|---|---|---|---|---|
| Mozilla Firefox Mozilla Thunderbird |
All versions prior to 154 | CVE-2026-75874 | 10 | Critical |
What has been observed?¶
The WASOC has not received any reports of exploitation of this vulnerability on Western Australian Government networks at the time of writing.
Recommendation¶
The WASOC recommends administrators apply the solutions as per vendor instructions to all affected devices within expected timeframes (refer Patch Management):
- Mozilla Firefox: https://www.mozilla.org/en-GB/security/advisories/mfsa2026-74/
- Mozilla Thunderbird: https://www.mozilla.org/en-GB/security/advisories/mfsa2026-78/