CVE-2026-16405: Information disclosure in the Networking: WebSockets component. This vulnerability was fixed in Firefox 153, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13.

highCVSS 7.5CVE-2026-16405

Information disclosure in the Networking: WebSockets component. This vulnerability was fixed in Firefox 153, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13.

Details

Source: NVD Recent CVEs (US · database · site)
Severity: high — CVSS 7.5
Published: 2026-07-21
Last updated: 2026-07-22
Exploitation: Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-16405

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-2026-164050.26% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 17% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-16405	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
unknownDSA-6394-1 firefox-esr - security updatedebian

CVE-2026-16405: Information disclosure in the Networking: WebSockets component. This vulnerability was fixed in Firefox 153, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13.

Details

Exploitation outlook

Referenced CVEs

Same CVEs, other sources

More from NVD Recent CVEs