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 0.57% 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.
public exploits
Unvetted proof-of-concept code on GitHub: 1 GitHub proof of concept
Listed so you can judge urgency, not as a recommendation to run anything. GitHub “proofs of concept” are unvetted: some are fake or carry malware. Exploit-DB marks the entries its staff verified.
cisa ssvc
- exploitation
- none
- automatable
- yes
- technical impact
- total
Assessed by CISA 23 Sept 2026 (SSVC 2.0.3).
timeline
- 23 Sept 2026Published
- 23 Sept 2026CISA SSVC assessment: exploitation none · same day later
- 24 Sept 2026Analysed by vulneraibility.com · 1 day later
- 30 Sept 2026CVE record last updated · 6 days later
- 23 Oct 2026First proof-of-concept repository on GitHub (unvetted) · 22 days later
- Advisorylists.apache.org /thread/45mxk8nj2q8pkhct6lfxkvtm2jpywrsp
- Linkopenwall.com /lists/oss-security/2026/09/23/21
sources
- CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
- NVD: CVSS and CPE data
- CISA Vulnrichment (ADP): SSVC decision points
- FIRST EPSS: exploit probability and percentile
- PoC-in-GitHub: GitHub repositories that claim a proof of concept
- Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.