CVE-2025-11721: 
NixOS vulnerability analysis and mitigation

CVE-2025-11721 is a high-impact memory safety vulnerability discovered in Firefox 143 and Thunderbird 143. The vulnerability was disclosed on October 14, 2025, and affects both Mozilla Firefox and Mozilla Thunderbird applications. This security issue was identified as a memory corruption bug that could potentially be exploited to execute arbitrary code (Mozilla Advisory, NVD).

The vulnerability is characterized as a memory safety bug that exhibits evidence of memory corruption. The technical assessment indicates a high severity level, with the potential for arbitrary code execution if sufficient effort is applied to exploit the vulnerability. The issue affects Firefox version 143 and Thunderbird version 143, with fixes implemented in version 144 of both applications (Mozilla Advisory).

The vulnerability presents a high-impact security risk, as successful exploitation could lead to arbitrary code execution on affected systems. This could potentially allow attackers to execute malicious code within the context of the affected applications, compromising the security of Firefox and Thunderbird users (Mozilla Advisory).

Mozilla has addressed this vulnerability by releasing security updates in Firefox 144 and Thunderbird 144. Users are advised to update their applications to these latest versions to mitigate the risk. The fix has been implemented across both Firefox and Thunderbird platforms (Mozilla Advisory, Mozilla Advisory).