Red Hat Product Security issued an advisory (RHSA-2025:8369) for Mozilla Firefox and Thunderbird addressing two out-of-bounds access vulnerabilities: CVE-2025-4918 occurs when resolving Promise objects, and CVE-2025-4919 occurs when optimizing linear sums. Both vulnerabilities are categorized under CWE-787 (Out-of-bounds Write). The advisory provides updated Firefox packages for Red Hat Enterprise Linux 9.2 Extended Update Support and related architectures. The update fixes these memory safety issues to prevent potential security risks. No CVSS base score is provided in the advisory, but the update is rated as Important.

The vulnerabilities allow out-of-bounds memory access in Firefox and Thunderbird, which can lead to potential memory corruption or crashes. While the exact impact details and exploitability are not provided, such issues typically pose risks of denial of service or potentially arbitrary code execution if exploited. Red Hat rates the security impact as Important, indicating a significant security concern that warrants prompt remediation.

Red Hat has released updated Firefox packages that fix these vulnerabilities for Red Hat Enterprise Linux 9.2 Extended Update Support and related variants. Users should apply the provided security update as detailed in Red Hat advisory RHSA-2025:8369 and the referenced article https://access.redhat.com/articles/11258. No additional mitigation steps are indicated or required beyond applying the official update.