Not ratedosv:RLSA-2026:80674

    Important: thunderbird security update

    Published Sources: OSV

    What is affected, what to do

    The available sources name no fixed version. Check the vendor guidance in the references below.

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

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    Priority

    No value is available for this vulnerability.

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    CVSS v3

    No value is available for this vulnerability.

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    EPSS score

    No value is available for this vulnerability.

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    Severity
    Not rated
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    30.00 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

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    no public PoC known
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

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    Published

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    Mozilla Thunderbird is a standalone mail and newsgroup client.

    Security Fix(es):

    • firefox: thunderbird: Use-after-free in the Graphics: Canvas2D component (CVE-2026-100832)

    • firefox: Use-after-free in the Layout: Text and Fonts component (CVE-2026-100784)

    • firefox: thunderbird: Privilege escalation in the DLL Services component (CVE-2026-100801)

    • firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Internationalization component (CVE-2026-100794)

    • firefox: thunderbird: Privilege escalation in the Address Bar component (CVE-2026-100820)

    • firefox: thunderbird: Use-after-free in the Graphics: Canvas2D component (CVE-2026-100777)

    • firefox: thunderbird: Information disclosure in the Networking: JAR component (CVE-2026-100766)

    • firefox: thunderbird: Use-after-free in the XSLT component (CVE-2026-100779)

    • firefox: thunderbird: Privilege escalation in the DOM: Service Workers component (CVE-2026-100807)

    • firefox: thunderbird: JIT miscompilation in the JavaScript: WebAssembly component (CVE-2026-100792)

    • firefox: Privilege escalation due to use-after-free in the Graphics: WebRender component (CVE-2026-100797)

    • firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the XPCOM component (CVE-2026-100819)

    • firefox: thunderbird: Use-after-free in the JavaScript: WebAssembly component (CVE-2026-100776)

    • firefox: thunderbird: Use-after-free in the Widget component (CVE-2026-100757)

    • firefox: Sandbox escape due to use-after-free in the Graphics component (CVE-2026-100786)

    • firefox: thunderbird: Information disclosure in the Networking component (CVE-2026-96869)

    • firefox: Sandbox escape due to use-after-free in the DOM: Content Processes component (CVE-2026-100770)

    • firefox: thunderbird: Use-after-free in the JavaScript: WebAssembly component (CVE-2026-100769)

    • firefox: Use-after-free in the DOM: Core & HTML component (CVE-2026-100791)

    • firefox: thunderbird: Sandbox escape due to use-after-free in the Widget: Gtk component (CVE-2026-100818)

    • firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics component (CVE-2026-100782)

    • firefox: firefox: Sandbox escape via use-after-free in DOM component (CVE-2026-100811)

    • firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-100772)

    • firefox: thunderbird: Uninitialized memory in the Storage: Quota Manager component (CVE-2026-100759)

    • firefox: Sandbox escape due to use-after-free in the DOM: Core & HTML component (CVE-2026-100778)

    • firefox: thunderbird: Sandbox escape in the DOM: Navigation component (CVE-2026-100758)

    • firefox: thunderbird: Sandbox escape in the Graphics component (CVE-2026-100775)

    • firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Graphics: WebRender component (CVE-2026-100781)

    • firefox: Use-after-free in the DOM: Core & HTML component (CVE-2026-100774)

    • firefox: thunderbird: Same-origin policy bypass in the WebExtensions component (CVE-2026-100803)

    • firefox: thunderbird: Use-after-free in the Graphics: Canvas2D component (CVE-2026-100789)

    • firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-100785)

    • firefox: thunderbird: Site isolation issue in the Panning and Zooming component (CVE-2026-100821)

    • firefox: thunderbird: Invalid pointer in the JavaScript: WebAssembly component (CVE-2026-100788)

    • firefox: thunderbird: Undefined behavior in the DOM: Streams component (CVE-2026-100771)

    • firefox: Sandbox escape due to use-after-free in the DOM: Content Processes component (CVE-2026-100762)

    • firefox: thunderbird: Use-after-free in the XSLT component (CVE-2026-100790)

    • firefox: thunderbird: Use-after-free in the Storage: IndexedDB component (CVE-2026-100773)

    • firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-100780)

    • firefox: thunderbird: Use-after-free in the Networking: Cache component (CVE-2026-100767)

    • firefox: thunderbird: Incorrect boundary conditions in the Audio/Video: Playback component (CVE-2026-100756)

    • firefox: thunderbird: Uninitialized memory in the Audio/Video component (CVE-2026-100783)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

    Source: OSV (Open Source Vulnerabilities)