ubuntu-cve-2025-12543
Vulnerability from osv_ubuntu
Published
2026-01-07 17:15
Modified
2026-05-20 15:16
Summary
Details

A flaw was found in the Undertow HTTP server core, which is used in WildFly, JBoss EAP, and other Java applications. The Undertow library fails to properly validate the Host header in incoming HTTP requests.As a result, requests containing malformed or malicious Host headers are processed without rejection, enabling attackers to poison caches, perform internal network scans, or hijack user sessions.

Severity
9.6 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L
9.6 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
N/A (UNKNOWN)
high
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro: https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "libundertow-java",
            "binary_version": "1.3.16-1ubuntu0.1~esm1"
          }
        ],
        "priority_reason": "user sesison takeover"
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:16.04:LTS",
        "name": "undertow",
        "purl": "pkg:deb/ubuntu/undertow@1.3.16-1ubuntu0.1~esm1?arch=source\u0026distro=esm-apps/xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.3.16-1ubuntu0.1~esm1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.3.4-1",
        "1.3.5-1",
        "1.3.7-1",
        "1.3.11-1",
        "1.3.16-1"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro: https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "libundertow-java",
            "binary_version": "1.4.23-3ubuntu0.1~esm1"
          }
        ],
        "priority_reason": "user sesison takeover"
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:18.04:LTS",
        "name": "undertow",
        "purl": "pkg:deb/ubuntu/undertow@1.4.23-3ubuntu0.1~esm1?arch=source\u0026distro=esm-apps/bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.4.23-3ubuntu0.1~esm1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "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"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro: https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "libundertow-java",
            "binary_version": "2.0.29-1ubuntu0.1~esm1"
          }
        ],
        "priority_reason": "user sesison takeover"
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:20.04:LTS",
        "name": "undertow",
        "purl": "pkg:deb/ubuntu/undertow@2.0.29-1ubuntu0.1~esm1?arch=source\u0026distro=esm-apps/focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.0.29-1ubuntu0.1~esm1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.0.23-1",
        "2.0.27-1",
        "2.0.28-1",
        "2.0.29-1"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro: https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "libundertow-java",
            "binary_version": "2.2.16-1ubuntu0.1~esm1"
          }
        ],
        "priority_reason": "user sesison takeover"
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:22.04:LTS",
        "name": "undertow",
        "purl": "pkg:deb/ubuntu/undertow@2.2.16-1ubuntu0.1~esm1?arch=source\u0026distro=esm-apps/jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.2.16-1ubuntu0.1~esm1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.2.8-1",
        "2.2.12-1",
        "2.2.13-1",
        "2.2.14-1",
        "2.2.16-1"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro: https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "libundertow-java",
            "binary_version": "2.3.8-2ubuntu0.1~esm1"
          }
        ],
        "priority_reason": "user sesison takeover"
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:24.04:LTS",
        "name": "undertow",
        "purl": "pkg:deb/ubuntu/undertow@2.3.8-2ubuntu0.1~esm1?arch=source\u0026distro=esm-apps/noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.3.8-2ubuntu0.1~esm1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.3.8-2"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libundertow-java",
            "binary_version": "2.3.18-2"
          }
        ],
        "priority_reason": "user sesison takeover"
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "undertow",
        "purl": "pkg:deb/ubuntu/undertow@2.3.18-2?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.3.18-1",
        "2.3.18-2"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "libundertow-java",
            "binary_version": "2.3.20-1ubuntu1"
          }
        ],
        "priority_reason": "user sesison takeover"
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "undertow",
        "purl": "pkg:deb/ubuntu/undertow@2.3.20-1ubuntu1?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.3.20-1ubuntu1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.3.18-2",
        "2.3.20-1"
      ]
    }
  ],
  "aliases": [],
  "details": "A flaw was found in the Undertow HTTP server core, which is used in WildFly, JBoss EAP, and other Java applications. The Undertow library fails to properly validate the Host header in incoming HTTP requests.As a result, requests containing malformed or malicious Host headers are processed without rejection, enabling attackers to poison caches, perform internal network scans, or hijack user sessions.",
  "id": "UBUNTU-CVE-2025-12543",
  "modified": "2026-05-20T15:16:02Z",
  "published": "2026-01-07T17:15:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2025-12543"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2025-12543"
    },
    {
      "type": "REPORT",
      "url": "https://access.redhat.com/security/cve/CVE-2025-12543"
    },
    {
      "type": "REPORT",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2408784"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/undertow-io/undertow/pull/1857"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/undertow-io/undertow/pull/1882"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/undertow-io/undertow/pull/1860"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/undertow-io/undertow/pull/1894"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-8144-1"
    }
  ],
  "related": [
    "USN-8144-1"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "high",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2025-12543"
  ]
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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