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CVE-2026-19879

CVE-2026-19879 · Io.undertow/undertow: undertow: http response header integrity issue due to character truncation

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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 5.3 · Medium · EPSS 0.4%

Published
Updated

Stack: system

Affected products and versions

  • red hat build of apache camel for spring boot 4

    No fix published

  • red hat enterprise linux 10

    No fix published

  • red hat enterprise linux 8

    No fix published

  • red hat enterprise linux 9

    No fix published

  • red hat jboss enterprise application platform 7

    No fix published

  • red hat jboss enterprise application platform 8

    No fix published

  • red hat jboss enterprise application platform expansion pack

    No fix published

  • red hat single sign-on 7

    No fix published

  • undertow Debian:14

    Versions
    • 1.3.11-1
    • 1.3.16-1
    • 1.3.19-1
    • 1.3.21-1
    • 1.3.23-1
    • 1.3.4-1
    • 1.3.5-1
    • 1.3.7-1
    • 1.4.0-1
    • 1.4.1-1
    • 1.4.18-1
    • 1.4.20-1
    • 1.4.21-1
    • 1.4.21-2
    • 1.4.22-1
    • 1.4.23-1
    • 1.4.23-2
    • 1.4.23-3
    • 1.4.25-1
    • 1.4.25-2
    • 1.4.3-1
    • 1.4.4-1
    • 1.4.6-1
    • 1.4.7-1
    • 1.4.8-1
    • 2.0.23-1
    • 2.0.25-1
    • 2.0.26-1
    • 2.0.27-1
    • 2.0.28-1
    • 2.0.29-1
    • 2.0.30-1
    • 2.1.0-1
    • 2.1.1-1
    • 2.1.3-1
    • 2.2.0-1
    • 2.2.10-1
    • 2.2.12-1
    • 2.2.13-1
    • 2.2.14-1
    • 2.2.16-1
    • 2.2.17-1
    • 2.2.18-1
    • 2.2.19-1
    • 2.2.2-1
    • 2.2.20-1
    • 2.2.21-1
    • 2.2.3-1
    • 2.2.4-1
    • 2.2.5-1
    • 2.2.8-1
    • 2.3.18-1
    • 2.3.18-2
    • 2.3.20-1
    • 2.3.8-1
    • 2.3.8-2
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • undertow Ubuntu:Pro:16.04:LTS

    Versions
    • 1.3.4-1
    • 1.3.5-1
    • 1.3.7-1
    • 1.3.11-1
    • 1.3.16-1
    • 1.3.16-1ubuntu0.1~esm1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • undertow Ubuntu:Pro:18.04:LTS

    Versions
    • 1.4.20-1
    • 1.4.21-1
    • 1.4.22-1
    • 1.4.23-1
    • 1.4.23-2build1
    • 1.4.23-3
    • 1.4.23-3ubuntu0.1~esm1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • undertow Ubuntu:Pro:20.04:LTS

    Versions
    • 2.0.23-1
    • 2.0.27-1
    • 2.0.28-1
    • 2.0.29-1
    • 2.0.29-1ubuntu0.1~esm1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • undertow Ubuntu:Pro:22.04:LTS

    Versions
    • 2.2.8-1
    • 2.2.12-1
    • 2.2.13-1
    • 2.2.14-1
    • 2.2.16-1
    • 2.2.16-1ubuntu0.1~esm1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • undertow Ubuntu:Pro:24.04:LTS

    Versions
    • 2.3.8-2
    • 2.3.8-2ubuntu0.1~esm1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • undertow Ubuntu:26.10

    Versions
    • 2.3.20-1ubuntu1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • undertow Ubuntu:26.04:LTS

    Versions
    • 2.3.18-2
    • 2.3.20-1
    • 2.3.20-1ubuntu1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

Original sources

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