An out-of-bounds write in "ClearKeyDecryptor" while decrypting some Clearkey-encrypted media content. The "ClearKeyDecryptor" code runs within the Gecko Media Plugin (GMP) sandbox. If a second mechanism is found to escape the sandbox, this vulnerability allows for the writing of arbitrary data within memory, resulting in a potentially exploitable crash. This vulnerability affects Firefox ESR < 45.9, Firefox ESR < 52.1, and Firefox < 53.
{
    "availability": "No subscription required",
    "binaries": [
        {
            "binary_name": "firefox",
            "binary_version": "53.0+build6-0ubuntu0.14.04.1"
        },
        {
            "binary_name": "firefox-dev",
            "binary_version": "53.0+build6-0ubuntu0.14.04.1"
        },
        {
            "binary_name": "firefox-globalmenu",
            "binary_version": "53.0+build6-0ubuntu0.14.04.1"
        },
        {
            "binary_name": "firefox-mozsymbols",
            "binary_version": "53.0+build6-0ubuntu0.14.04.1"
        },
        {
            "binary_name": "firefox-testsuite",
            "binary_version": "53.0+build6-0ubuntu0.14.04.1"
        }
    ]
}
          {
    "availability": "No subscription required",
    "binaries": [
        {
            "binary_name": "firefox",
            "binary_version": "53.0+build6-0ubuntu0.16.04.1"
        },
        {
            "binary_name": "firefox-dev",
            "binary_version": "53.0+build6-0ubuntu0.16.04.1"
        },
        {
            "binary_name": "firefox-globalmenu",
            "binary_version": "53.0+build6-0ubuntu0.16.04.1"
        },
        {
            "binary_name": "firefox-mozsymbols",
            "binary_version": "53.0+build6-0ubuntu0.16.04.1"
        },
        {
            "binary_name": "firefox-testsuite",
            "binary_version": "53.0+build6-0ubuntu0.16.04.1"
        }
    ]
}