CVE-2026-6786
Memory Corruption in Firefox and Thunderbird ESR Enables Code Execution
Publication date: 2026-04-26
Last updated on: 2026-04-28
Assigner: Mozilla Corporation
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| mozilla | firefox | to 150.0 (exc) |
| mozilla | firefox | From 140.0 (inc) to 140.10.0 (exc) |
| mozilla | thunderbird | From 140.0 (inc) to 140.10.0 (exc) |
Helpful Resources
Exploitability
| 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. |
| 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 Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.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
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability involves memory safety bugs found in specific versions of Firefox ESR, Thunderbird ESR, Firefox, and Thunderbird. These bugs can lead to memory corruption, which means that the software might access or modify memory in unintended ways. Such memory corruption could potentially be exploited by attackers to execute arbitrary code on the affected systems.
How can this vulnerability impact me? :
The impact of this vulnerability is significant because it allows attackers to potentially run arbitrary code on your system without your permission. This could lead to unauthorized access, data theft, system compromise, or other malicious activities. The CVSS base score of 8.1 indicates a high severity level, meaning the vulnerability poses a serious risk if exploited.
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, you should update affected software to the fixed versions.
- Upgrade Firefox to version 150 or later.
- Upgrade Firefox ESR to version 140.10 or later.
- Upgrade Thunderbird to version 150 or later.
- Upgrade Thunderbird ESR to version 140.10 or later.