The version of Firefox installed on the remote macOS or Mac OS X host is prior to 155.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-82 advisory.

  - Privilege escalation due to invalid pointer in the Graphics component. This vulnerability was fixed in     Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, and Firefox ESR 153.2. (CVE-2026-84131)

  - Sandbox escape due to use-after-free in the DOM: Security component. This vulnerability was fixed in     Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, and Firefox ESR 153.2. (CVE-2026-84121)

  - Use-after-free in the JavaScript: GC component. This vulnerability was fixed in Firefox 155 and Firefox     ESR 153.2. (CVE-2026-84118)

  - Sandbox escape due to use-after-free in the DOM: Navigation component. This vulnerability was fixed in     Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, and Firefox ESR 153.2. (CVE-2026-84119)

  - Use-after-free in the Audio/Video component. This vulnerability was fixed in Firefox 155, Firefox ESR     115.40, Firefox ESR 140.15, and Firefox ESR 153.2. (CVE-2026-84120)

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

The remote Fedora 44 host has packages installed that are affected by multiple vulnerabilities as referenced in the FEDORA-2026-42a3a95e62 advisory.

    NSS Release Notes

    Update NSS to 3.127.0

    - Bug 1869493 - Heap-buffer overflow in AES Keywrap.
    - Bug 2052210 - Generate additional test message for Thunderbird (HTML with remote image).
    - Bug 2052709 - Convert NSS 3.126 release notes to Markdown.
    - Bug 2053831 - clang format.
    - Bug 2054609 - remove cipher suite order exception from bug 946147.
    - Bug 2054714 - avoid leaking stale ECH outer extensions across HRR.
    - Bug 2054719 - fix content type tag for CMS AuthEnvelopedData plaintext.
    - Bug 2056291 - remove support for pre-v1.0 PKCS#12.
    - Bug 2056846 - Remove unused policy string callback to fix -Wunused-but-set-global.
    - Bug 2057184 - Enable -Wunused-but-set-variable/-global in werror.py.
    - Bug 2059176 - EC_DerivePublicKey() failure is not propagated in sftk_mkPrivKey().
    - Bug 2060118 - remove DH_GenParam support.
    - Bug 2060720 - Round ECH ClientHelloInner padding up to a multiple of 32.
    - Bug 2061107 - restore pkcs12.h for source compatibility.
    - Bug 2063071 - make selfserv listen on IPv6 wildcard on dual-stack hosts.

    https://firefox-source-docs.mozilla.org/security/nss/releases/nss_3_127.html

    - Updated Firefox to latest release (155.0)

Tenable has extracted the preceding description block directly from the Fedora 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 Thunderbird installed on the remote Windows host is prior to 155.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-86 advisory.

  - Internally found bugs present in Thunderbird 154, Thunderbird ESR 153.1 and Thunderbird ESR 140.14. Some     of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that     with enough effort some of these could have been exploited. (CVE-2026-84143, CVE-2026-84145)

  - Triggering an error condition in certain MIME bodies would cause uninitialized memory to be used.
    (CVE-2026-84639)

  - A maliciously constructed mail header could lead to a one byte read past the end of a buffer.
    (CVE-2026-84640)

  - A malicious IMAP server can trigger use-after-free and heap-memory disclosure by sending a crafted ID     response. Heap contents can ultimately be persisted to prefs.js. (CVE-2026-84641)

  - The values of the mail.allowedattachmenthostnames advanced config setting were used in a regular     expression without escaping. For some possible valid hostnames, this could allow certain unintended     hostnames to also match and serve remote attachments. (CVE-2026-84642)

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

The remote Fedora 45 host has packages installed that are affected by multiple vulnerabilities as referenced in the FEDORA-2026-823e097aaa advisory.

    NSS Release Notes

    Update NSS to 3.127.0

    - Bug 1869493 - Heap-buffer overflow in AES Keywrap.
    - Bug 2052210 - Generate additional test message for Thunderbird (HTML with remote image).
    - Bug 2052709 - Convert NSS 3.126 release notes to Markdown.
    - Bug 2053831 - clang format.
    - Bug 2054609 - remove cipher suite order exception from bug 946147.
    - Bug 2054714 - avoid leaking stale ECH outer extensions across HRR.
    - Bug 2054719 - fix content type tag for CMS AuthEnvelopedData plaintext.
    - Bug 2056291 - remove support for pre-v1.0 PKCS#12.
    - Bug 2056846 - Remove unused policy string callback to fix -Wunused-but-set-global.
    - Bug 2057184 - Enable -Wunused-but-set-variable/-global in werror.py.
    - Bug 2059176 - EC_DerivePublicKey() failure is not propagated in sftk_mkPrivKey().
    - Bug 2060118 - remove DH_GenParam support.
    - Bug 2060720 - Round ECH ClientHelloInner padding up to a multiple of 32.
    - Bug 2061107 - restore pkcs12.h for source compatibility.
    - Bug 2063071 - make selfserv listen on IPv6 wildcard on dual-stack hosts.

    https://firefox-source-docs.mozilla.org/security/nss/releases/nss_3_127.html

    - Updated Firefox to latest release (155.0)

Tenable has extracted the preceding description block directly from the Fedora 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 remote Fedora 44 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-379e77483b advisory.

    Update to latest stable upstream version.

Tenable has extracted the preceding description block directly from the Fedora 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 Unity Linux 20 host has a package installed that is affected by a vulnerability as referenced in the UTSA-2026-130367 advisory.

    Incorrect boundary conditions in the Layout: Grid component. This vulnerability was fixed in Firefox 155     and Thunderbird 155.

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

Note that Nessus has not tested for this issue 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.

  - Incorrect boundary conditions in the Layout: Grid component. This vulnerability was fixed in Firefox 155     and Thunderbird 155. (CVE-2026-84126)

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

The version of Thunderbird installed on the remote macOS or Mac OS X host is prior to 155.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-86 advisory.

  - Internally found bugs present in Thunderbird 154, Thunderbird ESR 153.1 and Thunderbird ESR 140.14. Some     of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that     with enough effort some of these could have been exploited. (CVE-2026-84143, CVE-2026-84145)

  - Triggering an error condition in certain MIME bodies would cause uninitialized memory to be used.
    (CVE-2026-84639)

  - A maliciously constructed mail header could lead to a one byte read past the end of a buffer.
    (CVE-2026-84640)

  - A malicious IMAP server can trigger use-after-free and heap-memory disclosure by sending a crafted ID     response. Heap contents can ultimately be persisted to prefs.js. (CVE-2026-84641)

  - The values of the mail.allowedattachmenthostnames advanced config setting were used in a regular     expression without escaping. For some possible valid hostnames, this could allow certain unintended     hostnames to also match and serve remote attachments. (CVE-2026-84642)

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

The remote Fedora 45 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-aa0e0deed1 advisory.

    Update to latest stable upstream version.

Tenable has extracted the preceding description block directly from the Fedora 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 Windows host is prior to 155.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-82 advisory.

  - Privilege escalation due to invalid pointer in the Graphics component. This vulnerability was fixed in     Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, and Firefox ESR 153.2. (CVE-2026-84131)

  - Sandbox escape due to use-after-free in the DOM: Security component. This vulnerability was fixed in     Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, and Firefox ESR 153.2. (CVE-2026-84121)

  - Use-after-free in the JavaScript: GC component. This vulnerability was fixed in Firefox 155 and Firefox     ESR 153.2. (CVE-2026-84118)

  - Sandbox escape due to use-after-free in the DOM: Navigation component. This vulnerability was fixed in     Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, and Firefox ESR 153.2. (CVE-2026-84119)

  - Use-after-free in the Audio/Video component. This vulnerability was fixed in Firefox 155, Firefox ESR     115.40, Firefox ESR 140.15, and Firefox ESR 153.2. (CVE-2026-84120)

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

The remote Fedora 43 host has packages installed that are affected by multiple vulnerabilities as referenced in the FEDORA-2026-208add2041 advisory.

    NSS Release Notes

    Update NSS to 3.127.0

    - Bug 1869493 - Heap-buffer overflow in AES Keywrap.
    - Bug 2052210 - Generate additional test message for Thunderbird (HTML with remote image).
    - Bug 2052709 - Convert NSS 3.126 release notes to Markdown.
    - Bug 2053831 - clang format.
    - Bug 2054609 - remove cipher suite order exception from bug 946147.
    - Bug 2054714 - avoid leaking stale ECH outer extensions across HRR.
    - Bug 2054719 - fix content type tag for CMS AuthEnvelopedData plaintext.
    - Bug 2056291 - remove support for pre-v1.0 PKCS#12.
    - Bug 2056846 - Remove unused policy string callback to fix -Wunused-but-set-global.
    - Bug 2057184 - Enable -Wunused-but-set-variable/-global in werror.py.
    - Bug 2059176 - EC_DerivePublicKey() failure is not propagated in sftk_mkPrivKey().
    - Bug 2060118 - remove DH_GenParam support.
    - Bug 2060720 - Round ECH ClientHelloInner padding up to a multiple of 32.
    - Bug 2061107 - restore pkcs12.h for source compatibility.
    - Bug 2063071 - make selfserv listen on IPv6 wildcard on dual-stack hosts.

    https://firefox-source-docs.mozilla.org/security/nss/releases/nss_3_127.html

    - Updated Firefox to latest upstream (155.0)

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

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
342201	Mozilla Firefox < 155.0	Nessus	MacOS X Local Security Checks	9/1/2026	9/11/2026	critical
342567	Fedora 44 : firefox / nss (2026-42a3a95e62)	Nessus	Fedora Local Security Checks	9/3/2026	9/11/2026	critical
342256	Mozilla Thunderbird < 155.0	Nessus	Windows	9/1/2026	10/21/2026	critical
344870	Fedora 45 : firefox / nss (2026-823e097aaa)	Nessus	Fedora Local Security Checks	9/11/2026	9/11/2026	critical
348353	Fedora 44 : thunderbird (2026-379e77483b)	Nessus	Fedora Local Security Checks	9/20/2026	9/20/2026	critical
366289	Unity Linux 20.1070e Security Update: firefox (UTSA-2026-130367)	Nessus	Unity Linux Local Security Checks	10/15/2026	10/15/2026	medium
342296	Linux Distros Unpatched Vulnerability : CVE-2026-84126	Nessus	Misc.	9/2/2026	9/2/2026	medium
342261	Mozilla Thunderbird < 155.0	Nessus	MacOS X Local Security Checks	9/1/2026	10/21/2026	critical
348331	Fedora 45 : thunderbird (2026-aa0e0deed1)	Nessus	Fedora Local Security Checks	9/19/2026	9/19/2026	critical
342204	Mozilla Firefox < 155.0	Nessus	Windows	9/1/2026	9/11/2026	critical
342518	Fedora 43 : firefox / nss (2026-208add2041)	Nessus	Fedora Local Security Checks	9/3/2026	10/9/2026	critical

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