CVE-2026-16388: Sandbox escape in the DOM: Networking component. This vulnerability was fixed in Firefox 153 and Thunderbird 153.

criticalCVSS 9.8CVE-2026-16388

Sandbox escape in the DOM: Networking component. This vulnerability was fixed in Firefox 153 and Thunderbird 153.

Details

Source: NVD Recent CVEs (US · database · site)
Severity: critical — CVSS 9.8
Published: 2026-07-21
Last updated: 2026-07-24
Exploitation: Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-16388

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-2026-163880.38% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 30% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-16388	coverage & exploitation status	NVD · CVE.org

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
unknownMultiple vulnerabilities in Mozilla Thunderbird (July 23, 2026)cert-fr-avis
unknownMozilla Products Multiple Vulnerabilitieshkcert
unknownMultiple vulnerabilities in Mozilla products (July 22, 2026)cert-fr-avis

Recent advisories for Sandbox escape in

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.

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criticalCVE-2026-18015: Inappropriate implementation in Tint in Google Chrome on Mac prior to 151.0.7922.72 allowed a …nvd · 2026-07-30
criticalCVE-2026-17947: Use after free in WebSockets in Google Chrome prior to 151.0.7922.72 allowed a remote attacker…nvd · 2026-07-30
criticalCVE-2026-17924: Use after free in DNS in Google Chrome prior to 151.0.7922.72 allowed a remote attacker who ha…nvd · 2026-07-30
mediumCVE-2026-17891: Use after free in ANGLE in Google Chrome on Android prior to 151.0.7922.72 allowed a remote at…nvd · 2026-07-30
highCVE-2026-17888: Insufficient validation of untrusted input in WebUI in Google Chrome prior to 151.0.7922.72 al…nvd · 2026-07-30