Multiple vulnerabilities in Mozilla Thunderbird (July 23, 2026)

CSIRTS triage

What

Multiple vulnerabilities allow an attacker to cause remote arbitrary code execution, privilege escalation, and remote denial of service.

Who is affected

Users of Mozilla Thunderbird are affected.

Urgency

Remediation is urgent due to the potential for remote code execution.

Action

Update to the latest version of Thunderbird to fix these vulnerabilities.

AI-assisted analysis generated from the source advisory — verify against the original.

Details

Source

CERT-FR Avis de sécurité (FR · national-cert · site)

Severity

unknown

Published

2026-07-23

Exploitation

Not in CISA KEV at last sync

Language

Machine-translated to English — verify against the original

Original advisory: https://www.cert.ssi.gouv.fr/avis/CERTFR-2026-AVI-0913/

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-2026-163540.34% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 27% of all scored CVEs.
• Low exploitation riskCVE-2026-163590.26% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 18% of all scored CVEs.
• Low exploitation riskCVE-2026-157190.34% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 26% of all scored CVEs.
• Low exploitation riskCVE-2026-164090.29% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 21% of all scored CVEs.
• Low exploitation riskCVE-2026-163860.31% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 24% of all scored CVEs.
• Low exploitation riskCVE-2026-163770.39% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 31% of all scored CVEs.
• Low exploitation riskCVE-2026-163570.40% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 33% of all scored CVEs.
• Low exploitation riskCVE-2026-163870.20% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 11% of all scored CVEs.
• Low exploitation riskCVE-2026-163520.39% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 32% of all scored CVEs.
• Low exploitation riskCVE-2026-164060.24% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 16% of all scored CVEs.

Referenced CVEs

+12 more CVEs referenced in this advisory.

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

• high[NEW] [high] Mozilla Firefox and Firefox ESR: Multiple vulnerabilitiescert-bund
• medium[NEW] [medium] Mozilla Firefox: Multiple vulnerabilities allow unspecified attackcert-bund
• unknownDSA-6403-1 nss - security updatedebian
• highCVE-2026-14899: The code to parse MIME headers for display when forwarding a message (if the setting to view a…nvd
• unknownMozilla Products Multiple Vulnerabilitieshkcert
• unknownMultiple vulnerabilities in Mozilla products (July 22, 2026)cert-fr-avis
• unknownDSA-6394-1 firefox-esr - security updatedebian
• criticalCVE-2026-16412: Memory safety bugs present in Firefox ESR 140.12 and Firefox 152. Some of these bugs showed ev…nvd
• criticalCVE-2026-16410: JIT miscompilation in the JavaScript Engine: JIT component. This vulnerability was fixed in Fi…nvd
• highCVE-2026-16409: Invalid pointer in the Security: PSM component. This vulnerability was fixed in Firefox 153 an…nvd
• criticalCVE-2026-16408: Integer overflow in the Audio/Video: Playback component. This vulnerability was fixed in Firef…nvd
• criticalCVE-2026-16407: Mitigation bypass in the DOM: Service Workers component. This vulnerability was fixed in Firef…nvd

Recent advisories for Mozilla 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[UPDATE] [high] Mozilla Thunderbird, Firefox ESR and Firefox: Multiple vulnerabilitiescert-bund · 2026-07-22
• high[UPDATE] [high] Mozilla Firefox, Firefox ESR and Thunderbird: Multiple vulnerabilitiescert-bund · 2026-07-22
• high[UPDATE] [high] Mozilla Firefox and Thunderbird: Multiple vulnerabilitiescert-bund · 2026-07-21
• medium[UPDATE] [medium] Mozilla Thunderbird: Multiple vulnerabilitiescert-bund · 2026-07-03
• unknownMultiple vulnerabilities in Mozilla Thunderbird (July 2, 2026)cert-fr-avis · 2026-07-02
• criticalexploitedCVE-2016-9079: Mozilla Firefox, Firefox ESR, and Thunderbird Use-After-Free Vulnerabilitycisa-kev · 2023-06-22

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