[NEW] [high] Mozilla Firefox and Thunderbird: Multiple Vulnerabilities
An attacker can exploit multiple vulnerabilities in Mozilla Firefox and Thunderbird to escalate privileges, bypass security measures, disclose sensitive information, manipulate data, conduct spoofing attacks, possibly execute arbitrary code through memory corruption, or cause Denial of Service conditions.
CSIRTS triage
- What
- Multiple vulnerabilities in Mozilla Firefox and Thunderbird enable privilege escalation, security bypass, information disclosure, memory corruption with potential arbitrary code execution, and Denial of Service.
- Who is affected
- All users of Firefox and Thunderbird across all versions.
- Urgency
- High severity with multiple attack vectors including potential code execution; immediate patching is critical.
- Action
- Update Firefox and Thunderbird to the latest available version.
AI-assisted analysis generated from the source advisory — verify against the original.
Details
Original advisory: https://wid.cert-bund.de/portal/wid/securityadvisory?name=WID-SEC-2026-3132
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Low exploitation riskCVE-2026-163650.27% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 19% of all EPSS-scored CVEs.
- Low exploitation riskCVE-2026-163710.28% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 20% of all EPSS-scored CVEs.
- Low exploitation riskCVE-2026-749520.22% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 12% of all EPSS-scored CVEs.
- Low exploitation riskCVE-2026-758740.40% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 33% of all EPSS-scored CVEs.
Referenced CVEs
Same CVEs, other sources
How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.
- high[NEW] [high] Mozilla Firefox, Firefox ESR and Thunderbird: Multiple Vulnerabilitiescert-bund
- high[NEW] [high] Mozilla Firefox and Firefox ESR: Multiple vulnerabilitiescert-bund
- unknownMozilla Products Multiple Vulnerabilitieshkcert
- unknownDSA-6481-1 firefox-esr - security updatedebian
- unknownMultiple vulnerabilities in Mozilla products (02 September 2026)cert-fr-avis
- highCVE-2026-84642: The values of the mail.allowed_attachment_hostnames advanced config setting were used in a reg…nvd
- highCVE-2026-84641: A malicious IMAP server can trigger use-after-free and heap-memory disclosure by sending a cra…nvd
- highCVE-2026-84640: A maliciously constructed mail header could lead to a one byte read past the end of a buffer. …nvd
- criticalCVE-2026-84639: Triggering an error condition in certain MIME bodies would cause uninitialized memory to be us…nvd
- criticalCVE-2026-84637: Malicious calendar invitations could use file URI attachments to launch local or network-hoste…nvd
- highCVE-2026-84145: Internally found bugs present in Thunderbird 154, Thunderbird ESR 153.1 and Thunderbird ESR 14…nvd
- unknownCVE-2026-84144: Internally found bugs present in Thunderbird 154 and Thunderbird ESR 153.1. Some of these bugs…nvd
Recent advisories for Mozilla Firefox and Thunderbird
A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.
- high[NEW] [high] Mozilla Firefox, Firefox ESR and Thunderbird: Multiple Vulnerabilitiescert-bund · 2026-09-03
- high[UPDATE] [high] Mozilla Firefox, Firefox ESR and Thunderbird: Multiple vulnerabilitiescert-bund · 2026-08-17
- high[UPDATE] [high] Mozilla Thunderbird, Firefox ESR and Firefox: Multiple vulnerabilitiescert-bund · 2026-07-22
- high[UPDATE] [high] Mozilla Firefox and Thunderbird: Multiple vulnerabilitiescert-bund · 2026-07-21
- criticalexploitedCVE-2016-9079: Mozilla Firefox, Firefox ESR, and Thunderbird Use-After-Free Vulnerabilitycisa-kev · 2023-06-22
- criticalexploitedCVE-2019-11707: Mozilla Firefox and Thunderbird Type Confusion Vulnerabilitycisa-kev · 2022-05-23
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