ubuntu-cve-2026-55213
Vulnerability from osv_ubuntu
Published
2026-07-13 00:00
Modified
2026-07-13 00:00
Summary
Details

h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. Prior to commit edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1, when h2o processes a QPACK instruction sent from the peer over HTTP/3, lib/http3/qpack.c might allocate an on-stack buffer as large as approximately 800 KB by calling alloca, which exceeds the default pthread stack size used by musl libc and causes the h2o server to crash with a segmentation fault while touching the guard page. This issue is fixed in commit edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1.

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "h2o",
            "binary_version": "2.2.4+dfsg-1ubuntu0.1~esm2"
          },
          {
            "binary_name": "libh2o-dev-common",
            "binary_version": "2.2.4+dfsg-1ubuntu0.1~esm2"
          },
          {
            "binary_name": "libh2o-evloop0.13",
            "binary_version": "2.2.4+dfsg-1ubuntu0.1~esm2"
          },
          {
            "binary_name": "libh2o0.13",
            "binary_version": "2.2.4+dfsg-1ubuntu0.1~esm2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:18.04:LTS",
        "name": "h2o",
        "purl": "pkg:deb/ubuntu/h2o@2.2.4+dfsg-1ubuntu0.1~esm2?arch=source\u0026distro=esm-apps/bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.2.3+dfsg-2",
        "2.2.4+dfsg-1",
        "2.2.4+dfsg-1build1",
        "2.2.4+dfsg-1ubuntu0.1~esm2"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "h2o",
            "binary_version": "2.2.5+dfsg2-3ubuntu0.1~esm1"
          },
          {
            "binary_name": "libh2o-dev-common",
            "binary_version": "2.2.5+dfsg2-3ubuntu0.1~esm1"
          },
          {
            "binary_name": "libh2o-evloop0.13",
            "binary_version": "2.2.5+dfsg2-3ubuntu0.1~esm1"
          },
          {
            "binary_name": "libh2o0.13",
            "binary_version": "2.2.5+dfsg2-3ubuntu0.1~esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:20.04:LTS",
        "name": "h2o",
        "purl": "pkg:deb/ubuntu/h2o@2.2.5+dfsg2-3ubuntu0.1~esm1?arch=source\u0026distro=esm-apps/focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.2.5+dfsg2-3",
        "2.2.5+dfsg2-3build1",
        "2.2.5+dfsg2-3ubuntu0.1~esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "h2o",
            "binary_version": "2.2.5+dfsg2-6.1ubuntu2+esm1"
          },
          {
            "binary_name": "libh2o-dev-common",
            "binary_version": "2.2.5+dfsg2-6.1ubuntu2+esm1"
          },
          {
            "binary_name": "libh2o-evloop0.13",
            "binary_version": "2.2.5+dfsg2-6.1ubuntu2+esm1"
          },
          {
            "binary_name": "libh2o0.13",
            "binary_version": "2.2.5+dfsg2-6.1ubuntu2+esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:22.04:LTS",
        "name": "h2o",
        "purl": "pkg:deb/ubuntu/h2o@2.2.5+dfsg2-6.1ubuntu2+esm1?arch=source\u0026distro=esm-apps/jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.2.5+dfsg2-6",
        "2.2.5+dfsg2-6.1",
        "2.2.5+dfsg2-6.1ubuntu1",
        "2.2.5+dfsg2-6.1ubuntu2",
        "2.2.5+dfsg2-6.1ubuntu2+esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "h2o",
            "binary_version": "2.2.5+dfsg2-8.1ubuntu3"
          },
          {
            "binary_name": "libh2o-dev-common",
            "binary_version": "2.2.5+dfsg2-8.1ubuntu3"
          },
          {
            "binary_name": "libh2o-evloop0.13t64",
            "binary_version": "2.2.5+dfsg2-8.1ubuntu3"
          },
          {
            "binary_name": "libh2o0.13t64",
            "binary_version": "2.2.5+dfsg2-8.1ubuntu3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "h2o",
        "purl": "pkg:deb/ubuntu/h2o@2.2.5+dfsg2-8.1ubuntu3?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.2.5+dfsg2-7",
        "2.2.5+dfsg2-8",
        "2.2.5+dfsg2-8.1ubuntu1",
        "2.2.5+dfsg2-8.1ubuntu2",
        "2.2.5+dfsg2-8.1ubuntu3"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "dnsdist",
            "binary_version": "1.8.3-2ubuntu0.1~esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:24.04:LTS",
        "name": "dnsdist",
        "purl": "pkg:deb/ubuntu/dnsdist@1.8.3-2ubuntu0.1~esm1?arch=source\u0026distro=esm-apps/noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.8.0-1",
        "1.8.2-1",
        "1.8.2-2",
        "1.8.2-3",
        "1.8.3-1",
        "1.8.3-2",
        "1.8.3-2build1",
        "1.8.3-2build2",
        "1.8.3-2ubuntu0.1~esm1"
      ]
    }
  ],
  "aliases": [],
  "details": "h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. Prior to commit edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1, when h2o processes a QPACK instruction sent from the peer over HTTP/3, lib/http3/qpack.c might allocate an on-stack buffer as large as approximately 800 KB by calling alloca, which exceeds the default pthread stack size used by musl libc and causes the h2o server to crash with a segmentation fault while touching the guard page. This issue is fixed in commit edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1.",
  "id": "UBUNTU-CVE-2026-55213",
  "modified": "2026-07-13T00:00:00Z",
  "published": "2026-07-13T00:00:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-55213"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-55213"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/h2o/h2o/security/advisories/GHSA-432c-8xmj-frmq"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/h2o/h2o/commit/edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-55213"
  ]
}



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