CVE-2026-5735

Modified Modified - Updated After Analysis

Memory Corruption in Firefox 149.0.1 Enables Code Execution

Publication date: 2026-04-07

Last updated on: 2026-06-30

Assigner: Mozilla Corporation

Description

Memory safety bugs present in Firefox 149.0.1 and Thunderbird 149.0.1. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 149.0.2 and Thunderbird 149.0.2.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-04-07

Last Modified

2026-06-30

Generated

2026-07-06

AI Q&A

2026-04-07

EPSS Evaluated

2026-07-05

NVD

CVE-2026-5735

EUVD

EUVD-2026-19616

Affected Vendors & Products

Vendor	Product	Version / Range
mozilla	firefox	to 149.0.2 (exc)
mozilla	thunderbird	to 149.0.2 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-125	The product reads data past the end, or before the beginning, of the intended buffer.
CWE-787	The product writes data past the end, or before the beginning, of the intended buffer.

Attack-Flow Graph

Impact Analysis

If exploited, this vulnerability could allow an attacker to run arbitrary code on your system through Firefox or Thunderbird. This means the attacker could potentially take control of your computer, access sensitive information, install malware, or perform other malicious actions.

Mitigation Strategies

To mitigate this vulnerability, update Firefox and Thunderbird to version 149.0.2 or later, as the issue affects versions prior to 149.0.2.

Executive Summary

This vulnerability involves memory safety bugs found in Firefox version 149.0.1 and Thunderbird version 149.0.1. Some of these bugs showed signs of memory corruption, which means that the software could behave unpredictably or incorrectly due to improper handling of memory.

It is presumed that with sufficient effort, some of these memory corruption bugs could be exploited by an attacker to execute arbitrary code on the affected system.

The vulnerability affects Firefox versions earlier than 149.0.2.

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