Affects widely used Apache Tomcat; auth bypass in WebSocket endpoints can expose many enterprise web apps and is likely to be widely noticed and exploited.
CVE-2026-76183
Authentication bypass in Apache Tomcat WebSocket endpoints.
Is CVE-2026-76183 being exploited?
Not confirmed. CVE-2026-76183 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.39% probability of exploitation in the next 30 days.
How severe is CVE-2026-76183?
CVE-2026-76183 is rated Critical with a CVSS score of 9.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-76183?
Yes. A fix has been recorded for CVE-2026-76183. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-76183 affect?
CVE-2026-76183 affects Apache Tomcat 11.0.0-M1 through 11.0.25, Apache Tomcat 10.1.0-M1 through 10.1.59, Apache Tomcat 9.0.0-M1 through 9.0.121, Known affected EOS: 8.5.0–8.5.100, 7.0.43–7.0.109. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-76183?
Upgrade to 11.0.26, 10.1.60 or 9.0.122 immediately
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Bypass WebSocket security constraints to access/operate protected endpoints, enabling unauthorized access, data exposure, and potential session misuse.
Immediate action required
- affected>= 11.0.0-M1 and <= 11.0.25
- affected>= 10.1.0-M1 and <= 10.1.59
- affected>= 9.0.0.M1 and <= 9.0.121
- affected>= 8.5.0 and <= 8.5.100
- affected>= 7.0.43 and <= 7.0.109
- affected< 7.0.43
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.