Jetty is a widely used Java web server; this request smuggling can bypass proxies/WAFs and impact many enterprise web apps.
CVE-2026-19203
Jetty HTTP request smuggling via LF-only chunked parsing.
Is CVE-2026-19203 being exploited?
Not confirmed. CVE-2026-19203 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 0.29% probability of exploitation in the next 30 days.
How severe is CVE-2026-19203?
CVE-2026-19203 is rated High with a CVSS score of 8.3. 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-2026-19203?
Yes. A fix has been recorded for CVE-2026-19203. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-19203 affect?
CVE-2026-19203 affects Eclipse Jetty server and servlet container, Applications using Jetty-based servers, Proxies, caches, and WAFs in front of Jetty. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-19203?
Upgrade Jetty to fixed release; enforce strict HTTP compliance or WAF mitigations.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
HTTP request smuggling allowing cache poisoning, proxy/WAF bypass, request hijack and potential data exfiltration.
Immediate action required
- affected>= 12.1.0 and <= 12.1.11
- affected>= 12.0.0 and <= 12.0.37
- affected>= 11.0.0 and <= 11.0.31
- affected>= 10.0.0 and <= 10.0.31
- affected>= 9.4.0 and <= 9.4.63
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.