CVE-2026-28367
Undertow header smuggling via \r\r\r terminator enables request tampering.
Is CVE-2026-28367 being exploited?
Not confirmed. CVE-2026-28367 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 0.71% probability of exploitation in the next 30 days.
How severe is CVE-2026-28367?
CVE-2026-28367 is rated High with a CVSS score of 8.7. 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-2026-28367?
Yes. A fix has been recorded for CVE-2026-28367. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-28367 affect?
CVE-2026-28367 affects Undertow Web Server, WildFly/JBoss stacks using Undertow, Proxies vulnerable to smuggling via \r\r\r (older Apache Traffic Server, Google Cloud Classic Load Balancer). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-28367?
Patch/upgrade Undertow stacks; review proxy configs.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote attacker can smuggle HTTP requests via the header terminator, potentially bypassing proxies and manipulating web traffic.
Patch when possible