When importing resources using Web Workers, error messages would distinguish the difference between <code>application/javascript</code> responses and non-script responses. This could have been abused to learn information cross-origin. This vulnerability affects Firefox < 97, Thunderbird < 91.6, and Firefox ESR < 91.6.
{
    "availability": "No subscription required",
    "binaries": [
        {
            "binary_name": "firefox",
            "binary_version": "97.0+build2-0ubuntu0.18.04.1"
        },
        {
            "binary_name": "firefox-dev",
            "binary_version": "97.0+build2-0ubuntu0.18.04.1"
        },
        {
            "binary_name": "firefox-geckodriver",
            "binary_version": "97.0+build2-0ubuntu0.18.04.1"
        },
        {
            "binary_name": "firefox-mozsymbols",
            "binary_version": "97.0+build2-0ubuntu0.18.04.1"
        }
    ]
}{
    "availability": "No subscription required",
    "binaries": [
        {
            "binary_name": "thunderbird",
            "binary_version": "1:91.7.0+build2-0ubuntu0.18.04.1"
        },
        {
            "binary_name": "thunderbird-dev",
            "binary_version": "1:91.7.0+build2-0ubuntu0.18.04.1"
        },
        {
            "binary_name": "thunderbird-gnome-support",
            "binary_version": "1:91.7.0+build2-0ubuntu0.18.04.1"
        },
        {
            "binary_name": "thunderbird-mozsymbols",
            "binary_version": "1:91.7.0+build2-0ubuntu0.18.04.1"
        },
        {
            "binary_name": "xul-ext-calendar-timezones",
            "binary_version": "1:91.7.0+build2-0ubuntu0.18.04.1"
        },
        {
            "binary_name": "xul-ext-gdata-provider",
            "binary_version": "1:91.7.0+build2-0ubuntu0.18.04.1"
        },
        {
            "binary_name": "xul-ext-lightning",
            "binary_version": "1:91.7.0+build2-0ubuntu0.18.04.1"
        }
    ]
}{
    "availability": "No subscription required",
    "binaries": [
        {
            "binary_name": "firefox",
            "binary_version": "97.0+build2-0ubuntu0.20.04.1"
        },
        {
            "binary_name": "firefox-dev",
            "binary_version": "97.0+build2-0ubuntu0.20.04.1"
        },
        {
            "binary_name": "firefox-geckodriver",
            "binary_version": "97.0+build2-0ubuntu0.20.04.1"
        },
        {
            "binary_name": "firefox-mozsymbols",
            "binary_version": "97.0+build2-0ubuntu0.20.04.1"
        }
    ]
}{
    "availability": "No subscription required",
    "binaries": [
        {
            "binary_name": "thunderbird",
            "binary_version": "1:91.7.0+build2-0ubuntu0.20.04.1"
        },
        {
            "binary_name": "thunderbird-dev",
            "binary_version": "1:91.7.0+build2-0ubuntu0.20.04.1"
        },
        {
            "binary_name": "thunderbird-gnome-support",
            "binary_version": "1:91.7.0+build2-0ubuntu0.20.04.1"
        },
        {
            "binary_name": "thunderbird-mozsymbols",
            "binary_version": "1:91.7.0+build2-0ubuntu0.20.04.1"
        },
        {
            "binary_name": "xul-ext-calendar-timezones",
            "binary_version": "1:91.7.0+build2-0ubuntu0.20.04.1"
        },
        {
            "binary_name": "xul-ext-gdata-provider",
            "binary_version": "1:91.7.0+build2-0ubuntu0.20.04.1"
        },
        {
            "binary_name": "xul-ext-lightning",
            "binary_version": "1:91.7.0+build2-0ubuntu0.20.04.1"
        }
    ]
}{
    "availability": "No subscription required",
    "binaries": [
        {
            "binary_name": "firefox",
            "binary_version": "97.0+build2-0ubuntu1"
        },
        {
            "binary_name": "firefox-dev",
            "binary_version": "97.0+build2-0ubuntu1"
        },
        {
            "binary_name": "firefox-geckodriver",
            "binary_version": "97.0+build2-0ubuntu1"
        },
        {
            "binary_name": "firefox-mozsymbols",
            "binary_version": "97.0+build2-0ubuntu1"
        }
    ]
}{
    "availability": "No subscription required",
    "binaries": [
        {
            "binary_name": "thunderbird",
            "binary_version": "1:91.6.1+build1-0ubuntu1"
        },
        {
            "binary_name": "thunderbird-dev",
            "binary_version": "1:91.6.1+build1-0ubuntu1"
        },
        {
            "binary_name": "thunderbird-gnome-support",
            "binary_version": "1:91.6.1+build1-0ubuntu1"
        },
        {
            "binary_name": "thunderbird-mozsymbols",
            "binary_version": "1:91.6.1+build1-0ubuntu1"
        },
        {
            "binary_name": "xul-ext-calendar-timezones",
            "binary_version": "1:91.6.1+build1-0ubuntu1"
        },
        {
            "binary_name": "xul-ext-gdata-provider",
            "binary_version": "1:91.6.1+build1-0ubuntu1"
        },
        {
            "binary_name": "xul-ext-lightning",
            "binary_version": "1:91.6.1+build1-0ubuntu1"
        }
    ]
}