There are packages installed that are affected by multiple vulnerabilities referenced in the following CVEs:

  - Mozilla developers reported memory safety bugs present in Firefox 92 and Firefox ESR 91.1. 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 affects Firefox < 93, Thunderbird < 91.2, and
    Firefox ESR < 91.2. (CVE-2021-38501)

  - crossbeam-deque is a package of work-stealing deques for building task schedulers when programming in
    Rust. In versions prior to 0.7.4 and 0.8.0, the result of the race condition is that one or more tasks in
    the worker queue can be popped twice instead of other tasks that are forgotten and never popped. If tasks
    are allocated on the heap, this can cause double free and a memory leak. If not, this still can cause a
    logical bug. Crates using `Stealer::steal`, `Stealer::steal_batch`, or `Stealer::steal_batch_and_pop` are
    affected by this issue. This has been fixed in crossbeam-deque 0.8.1 and 0.7.4. (CVE-2021-32810)

  - During operations on MessageTasks, a task may have been removed while it was still scheduled, resulting in
    memory corruption and a potentially exploitable crash. This vulnerability affects Thunderbird < 78.15,
    Thunderbird < 91.2, Firefox ESR < 91.2, Firefox ESR < 78.15, and Firefox < 93. (CVE-2021-38496)

  - Through use of reportValidity() and window.open(), a plain-text validation message could have been
    overlaid on another origin, leading to possible user confusion and spoofing attacks. This vulnerability
    affects Firefox < 93, Thunderbird < 91.2, and Firefox ESR < 91.2. (CVE-2021-38497)

  - During process shutdown, a document could have caused a use-after-free of a languages service object,
    leading to memory corruption and a potentially exploitable crash. This vulnerability affects Firefox < 93,
    Thunderbird < 91.2, and Firefox ESR < 91.2. (CVE-2021-38498)

The remote Ubuntu 18.04 LTS / 20.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-5107-1 advisory.

    Multiple security issues were discovered in Firefox. If a user were tricked into opening a specially     crafted website, an attacker could potentially exploit these to cause a denial of service, spoof another     origin, or execute arbitrary code.

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The version of Firefox installed on the remote macOS or Mac OS X host is prior to 93.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2021-43 advisory.

  - A use-after-free could have occurred when an HTTP2 session object was released on a different thread,     leading to memory corruption and a potentially exploitable crash. (CVE-2021-43535)

  - In the crossbeam crate, one or more tasks in the worker queue could have been be popped twice instead of     other tasks that are forgotten and never popped. If tasks are allocated on the heap, this could have     caused a double free and a memory leak. (CVE-2021-32810)

  - During operations on MessageTasks, a task may have been removed while it was still scheduled, resulting in     memory corruption and a potentially exploitable crash. (CVE-2021-38496)

  - Through use of <code>reportValidity()</code> and <code>window.open()</code>, a plain-text validation     message could have been overlaid on another origin, leading to possible user confusion and spoofing     attacks. (CVE-2021-38497)

  - During process shutdown, a document could have caused a use-after-free of a languages service object,     leading to memory corruption and a potentially exploitable crash. (CVE-2021-38498)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - Mozilla developers reported memory safety bugs present in Firefox 92. 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 affects Firefox < 93. (CVE-2021-38499)

Note that Nessus relies on the presence of the package as reported by the vendor.

The version of Firefox installed on the remote Windows host is prior to 93.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2021-43 advisory.

  - A use-after-free could have occurred when an HTTP2 session object was released on a different thread,     leading to memory corruption and a potentially exploitable crash. (CVE-2021-43535)

  - In the crossbeam crate, one or more tasks in the worker queue could have been be popped twice instead of     other tasks that are forgotten and never popped. If tasks are allocated on the heap, this could have     caused a double free and a memory leak. (CVE-2021-32810)

  - During operations on MessageTasks, a task may have been removed while it was still scheduled, resulting in     memory corruption and a potentially exploitable crash. (CVE-2021-38496)

  - Through use of <code>reportValidity()</code> and <code>window.open()</code>, a plain-text validation     message could have been overlaid on another origin, leading to possible user confusion and spoofing     attacks. (CVE-2021-38497)

  - During process shutdown, a document could have caused a use-after-free of a languages service object,     leading to memory corruption and a potentially exploitable crash. (CVE-2021-38498)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Published	Updated	Severity
404385	Alpine: multiple firefox packages: security update to 93.0-r0	Tenable Cloud Security	Alpine Linux Local Security Checks	10/31/2023	7/2/2026	critical
404385	Alpine: multiple firefox packages: security update to 93.0-r0	Tenable Self-Hosted Container Security	Alpine Linux Local Security Checks	10/31/2023	7/2/2026	critical
426761	Alpine: multiple librewolf packages: security update to 93.0-r0	Tenable Self-Hosted Container Security	Alpine Linux Local Security Checks	5/16/2025	7/2/2026	critical
426761	Alpine: multiple librewolf packages: security update to 93.0-r0	Tenable Cloud Security	Alpine Linux Local Security Checks	5/16/2025	7/2/2026	critical
153925	Ubuntu 18.04 LTS / 20.04 LTS : Firefox vulnerabilities (USN-5107-1)	Nessus	Ubuntu Local Security Checks	10/7/2021	8/27/2024	critical
153880	Mozilla Firefox < 93.0	Nessus	MacOS X Local Security Checks	10/5/2021	12/18/2025	critical
247917	Linux Distros Unpatched Vulnerability : CVE-2021-38499	Nessus	Misc.	8/11/2025	7/28/2026	high
153881	Mozilla Firefox < 93.0	Nessus	Windows	10/5/2021	12/18/2025	critical

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