CVE-2026-19879

Full vulnerability record from the local CVENow database.
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.
Severity
MEDIUM
CVSS score
5.3 (v3.1)
Vulnerability status
Awaiting Analysis
Source identifier
[email protected]
Published
2026-08-14 15:17:09.310000
Last modified
2026-11-05 20:17:55.373000
View original CVE JSON
{
  "id": "CVE-2026-19879",
  "sourceIdentifier": "[email protected]",
  "published": "2026-08-14T15:17:09.310",
  "lastModified": "2026-11-05T20:17:55.373",
  "vulnStatus": "Awaiting Analysis",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "Red Hat",
          "product": "Red Hat build of Apache Camel for Spring Boot 4",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "packageName": "undertow-core",
          "cpes": [
            "cpe:/a:redhat:camel_spring_boot:4"
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat build of Apache Camel for Spring Boot 4",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "packageName": "undertow-parent",
          "cpes": [
            "cpe:/a:redhat:camel_spring_boot:4"
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat build of Apache Camel for Spring Boot 4",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "packageName": "undertow-servlet",
          "cpes": [
            "cpe:/a:redhat:camel_spring_boot:4"
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat build of Apache Camel for Spring Boot 4",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "packageName": "undertow-websockets-jsr",
          "cpes": [
            "cpe:/a:redhat:camel_spring_boot:4"
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat Enterprise Linux 10",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "packageName": "moditect",
          "cpes": [
            "cpe:/a:redhat:enterprise_linux:10"
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat Enterprise Linux 8",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "packageName": "pki-core:10.6/resteasy",
          "cpes": [
            "cpe:/a:redhat:enterprise_linux:8"
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat Enterprise Linux 8",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "packageName": "pki-deps:10.6/resteasy",
          "cpes": [
            "cpe:/a:redhat:enterprise_linux:8"
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat Enterprise Linux 9",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "packageName": "resteasy",
          "cpes": [
            "cpe:/a:redhat:enterprise_linux:9"
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat JBoss Enterprise Application Platform 7",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/jbossnetwork/restricted/listSoftware.html",
          "packageName": "jboss-eap-7/eap74-els-openjdk11-openshift-rhel8",
          "cpes": [
            "cpe:/a:redhat:jboss_enterprise_application_platform:7"
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat JBoss Enterprise Application Platform 7",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/jbossnetwork/restricted/listSoftware.html",
          "packageName": "jboss-eap-7/eap74-els-openjdk17-openshift-rhel8",
          "cpes": [
            "cpe:/a:redhat:jboss_enterprise_application_platform:7"
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat JBoss Enterprise Application Platform 7",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/jbossnetwork/restricted/listSoftware.html",
          "packageName": "jboss-eap-7/eap74-els-openjdk8-openshift-rhel8",
          "cpes": [
            "cpe:/a:redhat:jboss_enterprise_application_platform:7"
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat JBoss Enterprise Application Platform 7",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/jbossnetwork/restricted/listSoftware.html",
          "packageName": "undertow-core",
          "cpes": [
            "cpe:/a:redhat:jboss_enterprise_application_platform:7"
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat JBoss Enterprise Application Platform 7",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/jbossnetwork/restricted/listSoftware.html",
          "packageName": "undertow-parent",
          "cpes": [
            "cpe:/a:redhat:jboss_enterprise_application_platform:7"
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat JBoss Enterprise Application Platform 7",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/jbossnetwork/restricted/listSoftware.html",
          "packageName": "undertow-servlet",
          "cpes": [
            "cpe:/a:redhat:jboss_enterprise_application_platform:7"
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat JBoss Enterprise Application Platform 7",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/jbossnetwork/restricted/listSoftware.html",
          "packageName": "undertow-websockets-jsr",
          "cpes": [
            "cpe:/a:redhat:jboss_enterprise_application_platform:7"
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat JBoss Enterprise Application Platform 8",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/jbossnetwork/restricted/listSoftware.html",
          "packageName": "undertow-core",
          "cpes": [
            "cpe:/a:redhat:jboss_enterprise_application_platform:8"
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat JBoss Enterprise Application Platform 8",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/jbossnetwork/restricted/listSoftware.html",
          "packageName": "undertow-servlet",
          "cpes": [
            "cpe:/a:redhat:jboss_enterprise_application_platform:8"
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat JBoss Enterprise Application Platform 8",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/jbossnetwork/restricted/listSoftware.html",
          "packageName": "undertow-websockets-jsr",
          "cpes": [
            "cpe:/a:redhat:jboss_enterprise_application_platform:8"
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat JBoss Enterprise Application Platform Expansion Pack",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/jbossnetwork/restricted/listSoftware.html",
          "packageName": "undertow-core",
          "cpes": [
            "cpe:/a:redhat:jbosseapxp"
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat JBoss Enterprise Application Platform Expansion Pack",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/jbossnetwork/restricted/listSoftware.html",
          "packageName": "undertow-servlet",
          "cpes": [
            "cpe:/a:redhat:jbosseapxp"
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat JBoss Enterprise Application Platform Expansion Pack",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/jbossnetwork/restricted/listSoftware.html",
          "packageName": "undertow-websockets-jsr",
          "cpes": [
            "cpe:/a:redhat:jbosseapxp"
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat Single Sign-On 7",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "packageName": "undertow-core",
          "cpes": [
            "cpe:/a:redhat:red_hat_single_sign_on:7"
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat Single Sign-On 7",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "packageName": "undertow-servlet",
          "cpes": [
            "cpe:/a:redhat:red_hat_single_sign_on:7"
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat Single Sign-On 7",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "packageName": "undertow-websockets-jsr",
          "cpes": [
            "cpe:/a:redhat:red_hat_single_sign_on:7"
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
          "baseScore": 5.3,
          "baseSeverity": "MEDIUM",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
          "availabilityImpact": "NONE"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 1.4
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-08-14T17:41:34.677014Z",
          "id": "CVE-2026-19879",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-681"
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://access.redhat.com/security/cve/CVE-2026-19879",
      "source": "[email protected]"
    },
    {
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2516038",
      "source": "[email protected]"
    }
  ]
}