Vulnerability-Lookup

UBUNTU-CVE-2026-44452 (CVE-2026-44452)

Vulnerability from osv_ubuntu – Published: 2026-07-16 23:16 – Updated: 2026-07-29 07:57 – Source website

Details

h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. Prior to commit 8dc37cb, when h2o receives a ClientHello message over TLS or QUIC and it contains a zero-length SNI extension, the h2o server runs over the zero-length hostname while trying to copy the hostname, assuming that it is NULL-terminated. This is a potential denial-of-service attack vector in sense that it might trigger segmentation violation. This issue has been fixed by commit 8dc37cb.

Severity

5.9 (Medium)


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

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-44452	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-44452	REPORT
	https://github.com/h2o/h2o/commit/8dc37cb1e6171f7…	REPORT
	https://github.com/h2o/h2o/security/advisories/GH…	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 8dc37cb, when h2o receives a ClientHello message over TLS or QUIC and it contains a zero-length SNI extension, the h2o server runs over the zero-length hostname while trying to copy the hostname, assuming that it is NULL-terminated. This is a potential denial-of-service attack vector in sense that it might trigger segmentation violation. This issue has been fixed by commit 8dc37cb.",
  "id": "UBUNTU-CVE-2026-44452",
  "modified": "2026-07-29T07:57:01Z",
  "published": "2026-07-16T23:16:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-44452"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-44452"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/h2o/h2o/commit/8dc37cb1e6171f7f772667618ea440696fed82c3"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/h2o/h2o/security/advisories/GHSA-w68q-rqwx-7wvq"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-44452"
  ]
}

CVE-2026-44452 (GCVE-0-2026-44452)

Vulnerability from cvelistv5 – Published: 2026-07-16 22:54 – Updated: 2026-07-17 14:03

Title

h2o is vulnerable to heap overrun

Summary

Severity

5.9 (Medium)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-17 14:03 UTC

CWE

CWE-125 - Out-of-bounds Read
CWE-170 - Improper Null Termination

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/8dc37cb1e6171f7…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
h2o	h2o	Affected: < 8dc37cb

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-44452",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-17T14:03:32.725590Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-07-17T14:03:52.757Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "h2o",
          "vendor": "h2o",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 8dc37cb"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. Prior to commit 8dc37cb, when h2o receives a ClientHello message over TLS or QUIC and it contains a zero-length SNI extension, the h2o server runs over the zero-length hostname while trying to copy the hostname, assuming that it is NULL-terminated. This is a potential denial-of-service attack vector in sense that it might trigger segmentation violation. This issue has been fixed by commit 8dc37cb."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 5.9,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-125",
              "description": "CWE-125: Out-of-bounds Read",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-170",
              "description": "CWE-170: Improper Null Termination",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-16T22:54:42.914Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/h2o/h2o/security/advisories/GHSA-w68q-rqwx-7wvq",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/h2o/h2o/security/advisories/GHSA-w68q-rqwx-7wvq"
        },
        {
          "name": "https://github.com/h2o/h2o/commit/8dc37cb1e6171f7f772667618ea440696fed82c3",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/h2o/h2o/commit/8dc37cb1e6171f7f772667618ea440696fed82c3"
        }
      ],
      "source": {
        "advisory": "GHSA-w68q-rqwx-7wvq",
        "discovery": "UNKNOWN"
      },
      "title": "h2o is vulnerable to heap overrun"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-44452",
    "datePublished": "2026-07-16T22:54:42.914Z",
    "dateReserved": "2026-05-06T15:49:25.192Z",
    "dateUpdated": "2026-07-17T14:03:52.757Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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Confirmed: The vulnerability has been validated from an analyst's perspective.
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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.

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.

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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.

Action not permitted

UBUNTU-CVE-2026-44452 (CVE-2026-44452)

CVE-2026-44452 (GCVE-0-2026-44452)

Tags

Sightings

Nomenclature

Related by attack behaviour