CVE-2025-9185
Published: 19 August 2025
Summary
CVE-2025-9185 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 8.1 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Client Execution (T1203); ranked at the 31.9th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 RA-5 (Vulnerability Monitoring and Scanning) and SI-16 (Memory Protection).
Threat & Defense at a Glance
Threat & Defense Details
Mitigating Controls (NIST 800-53 r5)AI
SI-2 mandates timely identification, mitigation, and correction of system flaws, directly requiring patching of the memory safety bugs in vulnerable Firefox and Thunderbird versions to prevent arbitrary code execution.
SI-16 enforces memory protection safeguards such as address space randomization and non-executable memory to block exploitation of memory corruption bugs like those in CVE-2025-9185.
RA-5 requires vulnerability scanning and remediation, enabling detection of outdated vulnerable browser versions and prompt patching to address this specific memory safety CVE.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Memory corruption bugs enabling remote arbitrary code execution in client applications (browser/mail client).
NVD Description
Memory safety bugs present in Firefox ESR 115.26, Firefox ESR 128.13, Thunderbird ESR 128.13, Firefox ESR 140.1, Thunderbird ESR 140.1, Firefox 141 and Thunderbird 141. Some of these bugs showed evidence of memory corruption and we presume that with enough…
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effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 142, Firefox ESR 115.27, Firefox ESR 128.14, Firefox ESR 140.2, Thunderbird 142, Thunderbird 128.14, and Thunderbird 140.2.
Deeper analysisAI
CVE-2025-9185 involves multiple memory safety bugs in Mozilla Firefox and Thunderbird products, specifically affecting Firefox ESR 115.26, Firefox ESR 128.13, Thunderbird ESR 128.13, Firefox ESR 140.1, Thunderbird ESR 140.1, Firefox 141, and Thunderbird 141. These bugs include instances showing evidence of memory corruption, which Mozilla presumes could be exploited with sufficient effort to achieve arbitrary code execution. The vulnerability is classified under CWE-119 (improper restriction of operations within the bounds of a memory buffer) and carries a CVSS v3.1 base score of 8.1.
Remote attackers can exploit this vulnerability over the network without user privileges or interaction, though it requires high attack complexity. Successful exploitation could result in high confidentiality, integrity, and availability impacts, potentially allowing arbitrary code execution within the browser or mail client context due to the memory corruption issues.
Mozilla's security advisories (MFSA 2025-64 through MFSA 2025-67) and related Bugzilla entries detail the fixes, which are available in updated releases: Firefox 142, Firefox ESR 115.27, Firefox ESR 128.14, Firefox ESR 140.2, Thunderbird 142, Thunderbird ESR 128.14, and Thunderbird ESR 140.2. Security practitioners should prioritize patching affected versions to mitigate the risk of code execution.
Details
- CWE(s)