# CVE-2026-12297 — Mozilla Firefox

> As of 2026-07-15, CVE-2026-12297 is a CRITICAL-severity vulnerability in Mozilla Firefox, CVSS v3.1 9.6, EPSS 0.3% (31.3th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-12297, most recently “Multiple Vulnerabilities in Firefox 152 Enable Remote Code Execution and Sandbox Escape (MFSA 2026-57)”.

**Last updated:** 2026-07-15

## What is CVE-2026-12297?

Sandbox escape due to incorrect boundary conditions in the Networking component. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12.

The record classifies CVE-2026-12297 under weakness classes [CWE-119](https://intel.threadlinqs.com/cwe/CWE-119), [CWE-653](https://cwe.mitre.org/data/definitions/653.html). 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-2026-12297 being exploited?

It currently carries a trending score of 14 in the Threadlinqs vulnerability feed.

## Affected products and versions

- [Mozilla](https://intel.threadlinqs.com/vendors/mozilla): Firefox, Thunderbird

## How to fix CVE-2026-12297

Vendor advisory: [https://www.mozilla.org/security/advisories/mfsa2026-57/](https://www.mozilla.org/security/advisories/mfsa2026-57/). Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.

## Threat activity tracking CVE-2026-12297

1 tracked threat in the Threadlinqs corpus references CVE-2026-12297, either in the campaign’s CVE list or as an indicator on the campaign record.

- [Multiple Vulnerabilities in Firefox 152 Enable Remote Code Execution and Sandbox Escape (MFSA 2026-57)](https://intel.threadlinqs.com/threat/TL-2026-0855) — HIGH · 2026-06-18

## Sources

Enriched from CVE.org, NVD, FIRST EPSS. Last verified by Threadlinqs on 2026-10-10. This product uses the NVD API but is not endorsed or certified by the NVD.

**Other references**

- [bugzilla.mozilla.org](https://bugzilla.mozilla.org/show_bug.cgi?id=2041610)
- [mozilla.org](https://www.mozilla.org/security/advisories/mfsa2026-57/)
- [mozilla.org (mfsa2026 58)](https://www.mozilla.org/security/advisories/mfsa2026-58/)
- [mozilla.org (mfsa2026 59)](https://www.mozilla.org/security/advisories/mfsa2026-59/)
- [mozilla.org (mfsa2026 60)](https://www.mozilla.org/security/advisories/mfsa2026-60/)

_Showing 5 of 6 recorded references._

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-12297
Full detection coverage and IOCs for threats exploiting CVE-2026-12297 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp