Important: thunderbird security, bug fix, and enhancement update
Published Sources: OSV
What is affected, what to do
Mozilla Thunderbird is a standalone mail and newsgroup client. Security Fix(es): * libexpat: denial of service via crafted XML input (CVE-2026-45186) * firefox: Mitigation bypass in the Enterprise Policies component (CVE-2026-109764) * firefox: Spoofing issue in the DOM: Web Serial component (CVE-2026-109770) * firefox: Mitigation bypass in the File Handling component (CVE-2026-109783) * firefox: thunderbird: Privilege escalation in the Application Update component (CVE-2026-109704) * firefox: Use-after-free in the XML component (CVE-2026-109718) * firefox: Information disclosure in the PDF Viewer component (CVE-2026-109742) * firefox: Incorrect boundary conditions in the JavaScript Engine component (CVE-2026-109715) * firefox: firefox: Sandbox escape via incorrect boundary conditions in Win32 widget (CVE-2026-109740) * firefox: Use-after-free in the Storage: IndexedDB component (CVE-2026-109706) * firefox: Use-after-free in the Crash Reporting component (CVE-2026-109713) * firefox: Use-after-free in the DOM: Core & HTML component (CVE-2026-109724) * firefox: Sandbox escape due to uninitialized memory in the DOM: Web Serial component (CVE-2026-109745) * firefox: Mitigation bypass in the File Handling component (CVE-2026-109782) * firefox: Information disclosure, privilege escalation in the Security: Process Sandboxing component (CVE-2026-109709) * firefox: Sandbox escape, site isolation issue due to incorrect boundary conditions, use-after-free in the Networking component (CVE-2026-109705) * firefox: Use-after-free in the Audio/Video: Playback component (CVE-2026-109738) * firefox: Sandbox escape due to race condition in the Networking component (CVE-2026-109757) * firefox: Use-after-free in the Storage: Bucket File System component (CVE-2026-109741) * firefox: Use-after-free in the JavaScript Engine: JIT component (CVE-2026-109729) * firefox: Other issue in the DOM: File component (CVE-2026-109744) * firefox: Incorrect boundary conditions in the JavaScript Engine component (CVE-2026-109716) * firefox: Race condition, use-after-free in the Graphics: CanvasWebGL component (CVE-2026-109719) * firefox: Incorrect boundary conditions in the Layout component (CVE-2026-109753) * firefox: Integer overflow in the Layout: Text and Fonts component (CVE-2026-109723) * firefox: Privilege escalation in the DOM: Navigation component (CVE-2026-109756) * firefox: JIT miscompilation in the JavaScript Engine: JIT component (CVE-2026-109733) * firefox: thunderbird: Mitigation bypass in the DOM: Security component (CVE-2026-109734) * firefox: Mitigation bypass in the File Handling component (CVE-2026-109763) * firefox: Sandbox escape due to incorrect boundary conditions in the Networking component (CVE-2026-109708) * firefox: Use-after-free in the DOM: Bindings (WebIDL) component (CVE-2026-109717) * firefox: Use-after-free in the DOM: Workers component (CVE-2026-109752) * firefox: Race condition in the XPCOM component (CVE-2026-109776) * firefox: Sandbox escape due to use-after-free in the Networking component (CVE-2026-109707) * firefox: Mitigation bypass in the Networking: HTTP component (CVE-2026-109760) * firefox: JIT miscompilation in the JavaScript: WebAssembly component (CVE-2026-109720) * firefox: Information disclosure in the Storage: IndexedDB component (CVE-2026-109777) * firefox: Use-after-free in the SVG component (CVE-2026-109726) * firefox: Integer overflow in the Graphics component (CVE-2026-109730) * firefox: Use-after-free in the Audio/Video component (CVE-2026-109727) * firefox: Mitigation bypass in the Enterprise Policies component (CVE-2026-109737) * firefox: Mitigation bypass in the Enterprise Policies component (CVE-2026-109766) * firefox: Use-after-free in the DOM: Streams component (CVE-2026-109732) * firefox: Site isolation issue in the Networking component (CVE-2026-109759) * firefox: Privilege escalation in the WebExtensions component (CVE-2026-109778) * firefox: Incorrect boundary conditions in the SVG component (CVE-2026-109762) * firefox: Race condition, use-after-free in the Graphics: Text component (CVE-2026-109765) * firefox: Incorrect boundary conditions in the DOM: Editor component (CVE-2026-109754) * firefox: Information disclosure in the Networking component (CVE-2026-109751) * firefox: Use-after-free in the DOM: Core & HTML component (CVE-2026-109725) * firefox: Sandbox escape due to uninitialized memory in the Graphics component (CVE-2026-109712) * firefox: Use-after-free in the Graphics: Canvas2D component (CVE-2026-109711) * firefox: Frame poisoning in the Layout component (CVE-2026-109736) * firefox: JIT miscompilation in the JavaScript Engine: JIT component (CVE-2026-109722) * firefox: Information disclosure in the Networking component (CVE-2026-109767) * firefox: Denial-of-service in the WebRTC component (CVE-2026-109775) * firefox: Use-after-free in the DOM: Animation component (CVE-2026-109728) * firefox: Denial-of-service in the Printing: Output component (CVE-2026-109781) * firefox: thunderbird: Use-after-free in the Graphics: Text component (CVE-2026-109710) * firefox: thunderbird: Incorrect boundary conditions in the Graphics: Canvas2D component (CVE-2026-109731) * firefox: Incorrect boundary conditions in the JavaScript Engine: JIT component (CVE-2026-109721) * firefox: Privilege escalation in the Panning and Zooming component (CVE-2026-109743) Bug Fix(es) and Enhancement(s): * Thunderbird ESR 153 rebase [rhel-9.8.z] (JIRA:RHEL-175199) 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.
The available sources name no fixed version. Check the vendor guidance in the references below.
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CVSS v3
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- Severity
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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.
Read in glossary- 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.
Read in glossary- —
- 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): * libexpat: denial of service via crafted XML input (CVE-2026-45186) * firefox: Mitigation bypass in the Enterprise Policies component (CVE-2026-109764) * firefox: Spoofing issue in the DOM: Web Serial component (CVE-2026-109770) * firefox: Mitigation bypass in the File Handling component (CVE-2026-109783) * firefox: thunderbird: Privilege escalation in the Application Update component (CVE-2026-109704) * firefox: Use-after-free in the XML component (CVE-2026-109718) * firefox: Information disclosure in the PDF Viewer component (CVE-2026-109742) * firefox: Incorrect boundary conditions in the JavaScript Engine component (CVE-2026-109715) * firefox: firefox: Sandbox escape via incorrect boundary conditions in Win32 widget (CVE-2026-109740) * firefox: Use-after-free in the Storage: IndexedDB component (CVE-2026-109706) * firefox: Use-after-free in the Crash Reporting component (CVE-2026-109713) * firefox: Use-after-free in the DOM: Core & HTML component (CVE-2026-109724) * firefox: Sandbox escape due to uninitialized memory in the DOM: Web Serial component (CVE-2026-109745) * firefox: Mitigation bypass in the File Handling component (CVE-2026-109782) * firefox: Information disclosure, privilege escalation in the Security: Process Sandboxing component (CVE-2026-109709) * firefox: Sandbox escape, site isolation issue due to incorrect boundary conditions, use-after-free in the Networking component (CVE-2026-109705) * firefox: Use-after-free in the Audio/Video: Playback component (CVE-2026-109738) * firefox: Sandbox escape due to race condition in the Networking component (CVE-2026-109757) * firefox: Use-after-free in the Storage: Bucket File System component (CVE-2026-109741) * firefox: Use-after-free in the JavaScript Engine: JIT component (CVE-2026-109729) * firefox: Other issue in the DOM: File component (CVE-2026-109744) * firefox: Incorrect boundary conditions in the JavaScript Engine component (CVE-2026-109716) * firefox: Race condition, use-after-free in the Graphics: CanvasWebGL component (CVE-2026-109719) * firefox: Incorrect boundary conditions in the Layout component (CVE-2026-109753) * firefox: Integer overflow in the Layout: Text and Fonts component (CVE-2026-109723) * firefox: Privilege escalation in the DOM: Navigation component (CVE-2026-109756) * firefox: JIT miscompilation in the JavaScript Engine: JIT component (CVE-2026-109733) * firefox: thunderbird: Mitigation bypass in the DOM: Security component (CVE-2026-109734) * firefox: Mitigation bypass in the File Handling component (CVE-2026-109763) * firefox: Sandbox escape due to incorrect boundary conditions in the Networking component (CVE-2026-109708) * firefox: Use-after-free in the DOM: Bindings (WebIDL) component (CVE-2026-109717) * firefox: Use-after-free in the DOM: Workers component (CVE-2026-109752) * firefox: Race condition in the XPCOM component (CVE-2026-109776) * firefox: Sandbox escape due to use-after-free in the Networking component (CVE-2026-109707) * firefox: Mitigation bypass in the Networking: HTTP component (CVE-2026-109760) * firefox: JIT miscompilation in the JavaScript: WebAssembly component (CVE-2026-109720) * firefox: Information disclosure in the Storage: IndexedDB component (CVE-2026-109777) * firefox: Use-after-free in the SVG component (CVE-2026-109726) * firefox: Integer overflow in the Graphics component (CVE-2026-109730) * firefox: Use-after-free in the Audio/Video component (CVE-2026-109727) * firefox: Mitigation bypass in the Enterprise Policies component (CVE-2026-109737) * firefox: Mitigation bypass in the Enterprise Policies component (CVE-2026-109766) * firefox: Use-after-free in the DOM: Streams component (CVE-2026-109732) * firefox: Site isolation issue in the Networking component (CVE-2026-109759) * firefox: Privilege escalation in the WebExtensions component (CVE-2026-109778) * firefox: Incorrect boundary conditions in the SVG component (CVE-2026-109762) * firefox: Race condition, use-after-free in the Graphics: Text component (CVE-2026-109765) * firefox: Incorrect boundary conditions in the DOM: Editor component (CVE-2026-109754) * firefox: Information disclosure in the Networking component (CVE-2026-109751) * firefox: Use-after-free in the DOM: Core & HTML component (CVE-2026-109725) * firefox: Sandbox escape due to uninitialized memory in the Graphics component (CVE-2026-109712) * firefox: Use-after-free in the Graphics: Canvas2D component (CVE-2026-109711) * firefox: Frame poisoning in the Layout component (CVE-2026-109736) * firefox: JIT miscompilation in the JavaScript Engine: JIT component (CVE-2026-109722) * firefox: Information disclosure in the Networking component (CVE-2026-109767) * firefox: Denial-of-service in the WebRTC component (CVE-2026-109775) * firefox: Use-after-free in the DOM: Animation component (CVE-2026-109728) * firefox: Denial-of-service in the Printing: Output component (CVE-2026-109781) * firefox: thunderbird: Use-after-free in the Graphics: Text component (CVE-2026-109710) * firefox: thunderbird: Incorrect boundary conditions in the Graphics: Canvas2D component (CVE-2026-109731) * firefox: Incorrect boundary conditions in the JavaScript Engine: JIT component (CVE-2026-109721) * firefox: Privilege escalation in the Panning and Zooming component (CVE-2026-109743) Bug Fix(es) and Enhancement(s): * Thunderbird ESR 153 rebase [rhel-9.8.z] (JIRA:RHEL-175199) 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.