[UPDATE] [high] Mozilla Firefox and Thunderbird: Multiple vulnerabilities
A remote, anonymous attacker can exploit multiple vulnerabilities in Mozilla Firefox, Mozilla Firefox ESR, and Mozilla Thunderbird to execute arbitrary code, disclose information, bypass security restrictions (e.g., sandbox escape), deceive the user, escalate permissions, or cause a Denial-of-Service condition.
CSIRTS triage
- What
- Multiple vulnerabilities can be exploited to execute arbitrary code, disclose information, bypass security restrictions, escalate permissions, or cause a Denial-of-Service condition.
- Who is affected
- Users of Mozilla Firefox, Firefox ESR, and Thunderbird are affected.
- Urgency
- Remediation is urgent due to the high severity and potential for exploitation.
- Action
- Update to the latest version of Mozilla Firefox or Thunderbird.
AI-assisted analysis generated from the source advisory — verify against the original.
⚡ Watch Firefox
Get an email when a new Firefox advisory drops — max one per day, one-click unsubscribe.
Details
Original advisory: https://wid.cert-bund.de/portal/wid/securityadvisory?name=WID-SEC-2026-1606
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-2026-83880.24% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 16% of all EPSS-scored CVEs.
- Low exploitation riskCVE-2026-83910.30% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 23% of all EPSS-scored CVEs.
- Low exploitation riskCVE-2026-84010.31% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 24% of all EPSS-scored CVEs.
- Low exploitation riskCVE-2026-87060.19% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 9% of all EPSS-scored CVEs.
- Low exploitation riskCVE-2026-89450.37% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 30% of all EPSS-scored CVEs.
- Low exploitation riskCVE-2026-89460.56% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 44% of all EPSS-scored CVEs.
- Low exploitation riskCVE-2026-89470.41% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 35% of all EPSS-scored CVEs.
- Low exploitation riskCVE-2026-89480.42% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 35% of all EPSS-scored CVEs.
- Low exploitation riskCVE-2026-89490.58% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 45% of all EPSS-scored CVEs.
- Low exploitation riskCVE-2026-89500.19% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 9% of all EPSS-scored CVEs.
Referenced CVEs
Same CVEs, other sources
How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.
More from CERT-Bund (BSI) Security Advisories
- high[NEW] [high] Linux Kernel: Multiple vulnerabilities2026-08-25
- medium[NEW] [medium] libTIFF: Multiple Vulnerabilities2026-08-25
- high[NEW] [high] Contao: Multiple Vulnerabilities2026-08-25
- medium[NEW] [medium] Django: Multiple Vulnerabilities2026-08-25
- high[NEW] [high] Red Hat Enterprise Linux (Apicurio Registry): Multiple Vulnerabilities2026-08-25