CVE-2026-4720
Received Received - Intake
Memory Corruption in Firefox and Thunderbird Enables Code Execution

Publication date: 2026-03-24

Last updated on: 2026-04-13

Assigner: Mozilla Corporation

Description
Memory safety bugs present in Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148. 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, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.
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Meta Information
Published
2026-03-24
Last Modified
2026-04-13
Generated
2026-05-07
AI Q&A
2026-03-24
EPSS Evaluated
2026-05-05
NVD
EUVD
Affected Vendors & Products
Showing 4 associated CPEs
Vendor Product Version / Range
mozilla firefox to 149.0 (exc)
mozilla firefox to 140.9.0 (exc)
mozilla thunderbird to 149.0 (exc)
mozilla thunderbird to 140.9.0 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-120 The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability involves memory safety bugs found in Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148, and Thunderbird 148. Some of these bugs showed signs of memory corruption, which means that with enough effort, an attacker could potentially exploit them to execute arbitrary code on the affected systems.


How can this vulnerability impact me? :

The impact of this vulnerability could be severe because it may allow an attacker to run arbitrary code on your device. This could lead to unauthorized access, data theft, or control over your system if you are using affected versions of Firefox or Thunderbird.


How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:

I don't know


How can this vulnerability be detected on my network or system? Can you suggest some commands?

I don't know


What immediate steps should I take to mitigate this vulnerability?

I don't know


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