Answer in brief
CVE-2026-28369 records a High severity (CVSS 8.7) vulnerability in Undertow: undertow: request smuggling via malformed http request headers. The current sources do not mark it as known exploited. The current feed maps io.undertow:undertow-parent (maven), io.undertow:undertow-parent (maven). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 8.7. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps io.undertow:undertow-parent (maven), io.undertow:undertow-parent (maven). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| io.undertow:undertow-parentmaven | <=2.3.23.Final | Not reported |
| io.undertow:undertow-parentmaven | >=0 | Not reported |
Published upstream
Mar 27, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 21, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jun 11, 2026
A flaw was found in Undertow. When Undertow receives an HTTP request where the first header line starts with one or more spaces, it incorrectly processes the request by stripping these leading spaces. This behavior, which violates HTTP standards, can be exploited by a remote attacker to perform request smuggling. Request smuggling allows an attacker to bypass security mechanisms, access restricted information, or manipulate web caches, potentially leading to unauthorized actions or data exposure.
Quoted source text, attributed separately from HOL analysis.