What is CVE-2026-12296?
Sandbox escape in the Security: Process Sandboxing component. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12.
The record classifies CVE-2026-12296 under weakness classes CWE-693, CWE-403. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs a user to take an action first, and has high impact on confidentiality, integrity, availability. 2 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 116 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 9.6 — CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H - EPSS (FIRST)
- 0.3% probability of exploitation in the next 30 days, higher than 31.3% of all scored CVEs
- CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 6.1/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2026-06-16, last modified 2026-07-15
Is CVE-2026-12296 being exploited?
It currently carries a trending score of 14 in the Threadlinqs vulnerability feed.
Affected products and versions
- Mozilla: Firefox, Thunderbird
How to fix CVE-2026-12296
No vendor patch reference has been recorded for CVE-2026-12296 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.
Threat activity tracking CVE-2026-12296
1 tracked threat in the Threadlinqs corpus references CVE-2026-12296, either in the campaign’s CVE list or as an indicator on the campaign record.
Sources
Enriched from CVE.org, FIRST EPSS. Last verified by Threadlinqs on .