# CVE-2026-92061: Mozilla Firefox incorrect boundary conditions in process sandboxing

Source: https://junglewise.ai/threats/cve-2026-92061-mozilla-firefox-incorrect-boundary-conditions-in-process  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-15. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-92061 · Severity: critical · CVSS 9.8 · Published 2026-09-15

Firefox and Thunderbird contain incorrect boundary condition checks in their process sandboxing security component, which isolates browser processes to limit the impact of exploits. An attacker could potentially bypass these sandbox restrictions to access system resources or escalate privileges on an affected user's computer, undermining the browser's core security isolation mechanism.

Technologies: [Mozilla Firefox](https://junglewise.ai/threats/technologies/firefox), [Mozilla Thunderbird](https://junglewise.ai/threats/technologies/thunderbird). Vendors: [Mozilla](https://junglewise.ai/threats/vendors/mozilla).

## Quick answers

**Is CVE-2026-92061 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-92061 being exploited in the wild.

**How severe is CVE-2026-92061?** Critical severity, with a CVSS score of 9.8, published 15 September 2026.

**Which products and versions are affected?** Mozilla Firefox before 156; Mozilla Thunderbird before 156.

**Is there a fix for CVE-2026-92061?** A patch was published on 2026-09-15: Fixed in Firefox 156 and Thunderbird 156 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-92061 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-92061?** Check whether you run Mozilla Firefox or Mozilla Thunderbird at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An incorrect boundary condition vulnerability in the Security: Process Sandboxing component allows attackers to bypass sandbox restrictions through flawed memory access boundary checks. The vulnerability is reachable over the network without requiring user interaction or prior authentication. Successful exploitation could allow an attacker to escape the sandbox environment and gain unauthorized access to protected system resources or escalate privileges. The vulnerability has been patched in Firefox 156 and Thunderbird 156.

## Affected products

- Mozilla Firefox before 156
- Mozilla Thunderbird before 156

## Timeline

- 2026-09-15: disclosed
- 2026-09-15: patched: Fixed in Firefox 156 and Thunderbird 156

## References

- [https://bugzilla.mozilla.org/show_bug.cgi?id=2041758](https://bugzilla.mozilla.org/show_bug.cgi?id=2041758)
- [https://www.mozilla.org/security/advisories/mfsa2026-90/](https://www.mozilla.org/security/advisories/mfsa2026-90/)

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