CVE-2026-19879
MEDIUM
MEDIUM
Priority: 0.02
BB Relevance:
71/100
Published: 2026-08-14
Modified: 2026-11-05
First seen: 2026-11-05
Status: active
Attack Surface
Network
Low Complexity
No Auth
No Interaction
CVSS Vector Breakdown
AV:
Network
AC:
Low
PR:
None
UI:
None
S:
Unchanged
C:
None
I:
Low
A:
None
Description
A flaw was found in Undertow, an HTTP server, within its HTTP response header writing path. The `writeString()` method performs a silent narrowing cast from 16-bit Unicode characters to 8-bit bytes when writing HTTP response header values. A remote attacker can exploit this by supplying specific Unicode characters in user-controlled input that an application places into response headers. This can lead to the truncation of these characters into ASCII control characters or special symbols, potentially resulting in limited integrity impact or information disclosure if the application does not properly sanitize user input.
Weakness Classification (1)
References & Advisories (2)
vdb-entry
x_refsource_REDHAT
issue-tracking
x_refsource_REDHAT