Vulnerability-Lookup

ubuntu-cve-2026-55213

Vulnerability from osv_ubuntu

Published

2026-07-10 21:16

Modified

2026-07-15 17:53

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

URL

Type

	https://ubuntu.com/security/CVE-2026-55213	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-55213	REPORT
	https://github.com/h2o/h2o/security/advisories/GH…	REPORT
	https://github.com/h2o/h2o/commit/edd7a120bfc4af1…	REPORT

JSON

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": "2026-07-15T17:53:44Z",
  "published": "2026-07-10T21:16:00Z",
  "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"
  ]
}

CVE-2026-55213 (GCVE-0-2026-55213)

Vulnerability from cvelistv5 – Published: 2026-07-10 20:49 – Updated: 2026-07-13 14:14

Title

h2o: musl libc stack overflow (QPACK)

Summary

Severity

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-13 14:14 UTC

CWE

CWE-789 - Memory Allocation with Excessive Size Value

Assigner

GitHub_M mitre root

References

2 references

URL	Tags
https://github.com/h2o/h2o/security/advisories/GH…	x_refsource_CONFIRM
https://github.com/h2o/h2o/commit/edd7a120bfc4af1…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
h2o	h2o	Affected: < edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-55213",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-13T14:14:29.008624Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-07-13T14:14:45.685Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "h2o",
          "vendor": "h2o",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-789",
              "description": "CWE-789: Memory Allocation with Excessive Size Value",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-10T20:49:58.764Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/h2o/h2o/security/advisories/GHSA-432c-8xmj-frmq",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/h2o/h2o/security/advisories/GHSA-432c-8xmj-frmq"
        },
        {
          "name": "https://github.com/h2o/h2o/commit/edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/h2o/h2o/commit/edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1"
        }
      ],
      "source": {
        "advisory": "GHSA-432c-8xmj-frmq",
        "discovery": "UNKNOWN"
      },
      "title": "h2o: musl libc stack overflow (QPACK)"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-55213",
    "datePublished": "2026-07-10T20:49:58.764Z",
    "dateReserved": "2026-06-16T16:16:32.627Z",
    "dateUpdated": "2026-07-13T14:14:45.685Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

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.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.