CVE-2026-74949

Modified Modified - Updated After Analysis

Privilege Escalation in Firefox via Graphics Canvas2D Use-After-Free

Publication date: 2026-08-18

Last updated on: 2026-09-01

Assigner: Mozilla Corporation

Description

Privilege escalation due to use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-08-18

Last Modified

2026-09-01

Generated

2026-09-07

AI Q&A

2026-08-18

EPSS Evaluated

2026-09-06

NVD

CVE-2026-74949

EUVD

EUVD-2026-60755

Affected Vendors & Products

Vendor	Product	Version / Range
mozilla	thunderbird	From 141.0 (inc) to 153.1.0 (exc)
mozilla	thunderbird	to 140.14.0 (exc)
mozilla	firefox	to 140.14.0 (exc)
mozilla	firefox	From 141.0.0 (inc) to 153.1.0 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-416	The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

Attack-Flow Graph

Executive Summary

This is a privilege escalation vulnerability caused by a use-after-free bug in Firefox's Graphics: Canvas2D component. A use-after-free occurs when a program continues to use memory after it has been freed, potentially allowing attackers to execute arbitrary code or escalate privileges.

Detection Guidance

This vulnerability is specific to Firefox versions before 154, Firefox ESR 140.14, and Firefox ESR 153.1. To detect it, check your installed Firefox version using commands like 'firefox --version' or 'about:support' in Firefox. If your version is below the fixed versions, the system is vulnerable.

Impact Analysis

If exploited, this vulnerability could allow an attacker to gain elevated access to your system, run malicious code, or install unauthorized software. Users of affected Firefox versions are at risk if they visit a specially crafted webpage.

Compliance Impact

The provided CVE data does not specify how this vulnerability impacts compliance with standards like GDPR or HIPAA. The description focuses on technical details of the issue without addressing regulatory implications.

Mitigation Strategies

Update Firefox to version 154 or later, Firefox ESR to version 140.14 or later, or Firefox ESR to version 153.1 or later to address the use-after-free vulnerability in Graphics: Canvas2D.

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