Affects Apache Tomcat, a widely deployed Java web server; regression enables HTTP/2 request smuggling with a high CVSS score and broad impact.
CVE-2026-86350
HTTP/2 request-smuggling regression in Apache Tomcat causes header mix-ups.
Is CVE-2026-86350 being exploited?
Not confirmed. CVE-2026-86350 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.
How severe is CVE-2026-86350?
CVE-2026-86350 is rated Critical with a CVSS score of 9.1. 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-2026-86350?
Yes. A fix has been recorded for CVE-2026-86350. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-86350 affect?
CVE-2026-86350 affects Apache Tomcat 11.0.22 - 11.0.25, Apache Tomcat 10.1.55 - 10.1.59, Apache Tomcat 9.0.118 - 9.0.121, Fixed in 11.0.26, 10.1.60, 9.0.122. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-86350?
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.
HTTP/2 request/response smuggling causing header mix-up; can enable request hijack, cache poisoning, auth bypass, data leakage, and session takeover.
Immediate action required
- affected>= 11.0.22 and <= 11.0.25
- affected>= 10.1.55 and <= 10.1.59
- affected>= 9.0.118 and <= 9.0.121
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.