CVE-2026-106016
Description
A flaw was found in Mozilla Firefox and Thunderbird. A mitigation bypass in the File Handling component allows an attacker to bypass security protections. This vulnerability was fixed in Firefox 157.0.1 and Thunderbird 158.
Statement
A moderate-severity mitigation bypass was reported in the File Handling component of Mozilla Firefox, which is the component tracked for this flaw in Red Hat's records. The flaw bypasses a security protection mechanism in file handling; the public upstream record does not describe the specific attack vector or consequence because the Mozilla bug report is access-restricted, so those details cannot be verified. Mozilla, the upstream CNA, rates the issue as moderate and lists both Firefox and Thunderbird as affected upstream products. This differs meaningfully from the CVSS 3.1 score of 9.8 (Critical) added to the CVE record by CISA ADP enrichment, which does not reflect the upstream CNA assessment; no Red Hat impact or CVSS score has been set for this flaw. No Red Hat product affects have been recorded at this time, so the affected-product scope within the Red Hat portfolio is still to be determined through triage.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. Upstream fixed this issue in Firefox 157.0.1 and Thunderbird 158, so upgrading to a version that contains the upstream fix is the available remediation.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.5 | N/A | 9.8 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | Required | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | None | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Red Hat CVSS v3 Score Explanation
File handling mitigation bypass - requires user interaction with malicious file. Impact rated MODERATE per Mozilla mfsa2026-104 (upstream CNA assessment).
Understanding the Weakness (CWE)
Access Control
Technical Impact: Bypass Protection Mechanism
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