CVE-2025-8040
Published: 22 July 2025
Summary
CVE-2025-8040 is a high-severity Improper Restriction of Operations within the Bounds of a Memory Buffer (CWE-119) vulnerability in Mozilla Firefox. Its CVSS base score is 8.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Drive-by Compromise (T1189); ranked in the top 37.8% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SI-16 (Memory Protection) and SI-2 (Flaw Remediation).
Deeper analysis
CVE-2025-8040 is a set of memory safety bugs (CWE-119) affecting Firefox ESR 140.0, Thunderbird ESR 140.0, Firefox 140, and Thunderbird 140. These bugs involve improper restriction of operations within memory bounds, with some demonstrating evidence of memory corruption. Mozilla presumes that sufficient effort could enable exploitation for arbitrary code execution.
Attackers can exploit this vulnerability remotely over the network with low complexity and no required privileges, but it necessitates user interaction, such as visiting a malicious site or engaging with crafted content. Successful exploitation could result in high-impact confidentiality, integrity, and availability violations (CVSS 8.8: AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H), potentially allowing arbitrary code execution within the browser or mail client context.
Mozilla's security advisories (MFSA 2025-56, 59, 61, 63) and related Bugzilla entries detail the fixes applied in Firefox 141, Firefox ESR 140.1, Thunderbird 141, and Thunderbird 140.1. Security practitioners should prioritize updating affected installations to these patched versions to mitigate the risk.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-22360
Vulnerability details
Memory safety bugs present in Firefox ESR 140.0, Thunderbird ESR 140.0, Firefox 140 and Thunderbird 140. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to…
more
run arbitrary code. This vulnerability was fixed in Firefox 141, Firefox ESR 140.1, Thunderbird 141, and Thunderbird 140.1.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Memory corruption bugs directly enable remote arbitrary code execution in browser/mail client via malicious site/content (drive-by).
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly requires timely identification, reporting, and correction of flaws like the memory safety bugs in CVE-2025-8040 through patching to Firefox/Thunderbird 141/ESR 140.1.
Implements memory safeguards such as non-executable memory regions and address randomization to prevent exploitation of memory corruption bugs for arbitrary code execution.
Enables vulnerability scanning to identify and prioritize memory safety issues like CVE-2025-8040 in affected Firefox and Thunderbird installations.