CVE-2026-19879

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.

CVSS v3 5.3 MEDIUM

5.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 3.9 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact LOW

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://access.redhat.com/security/cve/CVE-2026-19879
https://bugzilla.redhat.com/show_bug.cgi?id=2516038

Configurations

No configuration.

History

No history.

Information

Published : 2026-08-14 15:17

Updated : 2026-08-14 19:07

NVD link : CVE-2026-19879

Mitre link : CVE-2026-19879

CVE.ORG link : CVE-2026-19879

JSON object : View

Products Affected

No product.

CWE

CWE-681

Incorrect Conversion between Numeric Types

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