CVE-2025-0247
Published: 07 January 2025
Summary
CVE-2025-0247 is a critical-severity Out-of-bounds Write (CWE-787) vulnerability in Mozilla Firefox. Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Client Execution (T1203); ranked in the top 4.5% 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-2025-0247 is a collection of memory safety bugs affecting Firefox 133 and Thunderbird 133. Several of the issues exhibited signs of memory corruption and are presumed to be exploitable for arbitrary code execution given sufficient attacker effort. The flaws are classified under CWE-787 and carry a CVSS 3.1 base score of 9.8.
An unauthenticated remote attacker can trigger the vulnerabilities over the network without user interaction, potentially achieving full code execution within the affected browser or mail client process. Successful exploitation would allow an attacker to read, modify, or delete data and execute arbitrary code with the privileges of the running application.
Mozilla addressed the issues in Firefox 134 and Thunderbird 134, as documented in MFSA2025-01 and MFSA2025-04. The advisories direct users to apply the updates promptly and reference the underlying Bugzilla entries for additional technical detail.
The associated EPSS score has remained flat at its peak value of 0.1917 since disclosure, indicating no material increase in observed exploitation interest.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-1579
Vulnerability details
Memory safety bugs present in Firefox 133 and Thunderbird 133. 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…
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fixed in Firefox 134 and Thunderbird 134.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Memory corruption bugs enabling remote arbitrary code execution in client software (browser/email) directly map to exploitation for client execution.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Mandates timely identification, reporting, and patching of flaws like the memory safety bugs in Firefox 133 and Thunderbird 133 to prevent arbitrary code execution.
Implements memory safeguards such as address space layout randomization and data execution prevention to directly mitigate exploitation of memory corruption bugs like CWE-787 out-of-bounds writes.
Enables vulnerability scanning to identify and prioritize deployed instances of vulnerable Firefox 133 or Thunderbird 133 for remediation.