CVE-2026-28367: Undertow is Vulnerable to HTTP Request/Response Smuggling

March 27, 2026 (updated March 31, 2026)

A flaw was found in Undertow. A remote attacker can exploit this vulnerability by sending \r\r\r as a header block terminator. This can be used for request smuggling with certain proxy servers, such as older versions of Apache Traffic Server and Google Cloud Classic Application Load Balancer, potentially leading to unauthorized access or manipulation of web requests.

References

access.redhat.com/security/cve/CVE-2026-28367
bugzilla.redhat.com/show_bug.cgi?id=2443260
github.com/advisories/GHSA-3gv6-g396-9v4r
github.com/undertow-io/undertow
nvd.nist.gov/vuln/detail/CVE-2026-28367

Code Behaviors & Features

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