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CVE-2026-28367

Undertow: undertow: request smuggling via `\r\r\r` as a header block terminator

CVSS 3.1 8.7 HIGHCheck source for fixed versionsKEV status unknown
Original advisory

cve-program · CVE-2026-28367

Published

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.

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Affected versions, risk and source history

Exploitation and risk

Source status

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cve-program · CVE-2026-28367

Published

Undertow: undertow: request smuggling via `\r\r\r` as a header block terminator

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.

Source published
27 Mar 2026 16:13:05 UTC
Source modified
4 Nov 2026 22:18:52 UTC
Saved here
4 Nov 2026 23:54:02 UTC
Source terms
CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

Source: cve-program · CVE Program Terms of Use. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS 3.1 · 8.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N

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