Vulnerability-Lookup

SUSE-SU-2026:23563-1

Vulnerability from csaf_suse - Published: 2026-08-30 14:34 - Updated: 2026-09-29 17:27

Summary

Security update for python-h2

Severity

Moderate

Notes

Title of the patch: Security update for python-h2

Description of the patch: This update for python-h2 fixes the following issue: - CVE-2026-71554: duplicate `Host` headers are accepted and forwarded to consuming applications, which can lead to request smuggling (bsc#1274386).

Patchnames: SUSE-SLES-16.0-1549

CVE-2026-71554

5.3 (Medium)


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

Affected products

Recommended 2 products

Product	Identifier	Version	Remediation
Unresolved product id: SUSE Linux Enterprise Server 16.0:python313-h2-0:4.2.0-160000.4.1.noarch		—	Vendor Fix
Unresolved product id: SUSE Linux Enterprise Server for SAP applications 16.0:python313-h2-0:4.2.0-160000.4.1.noarch		—	Vendor Fix

Threats

Impact moderate

References

8 references

URL	Category
https://www.suse.com/support/security/rating/	external
https://ftp.suse.com/pub/projects/security/csaf/s…	self
https://www.suse.com/support/update/announcement/…	self
https://lists.suse.com/pipermail/sle-security-upd…	self
https://bugzilla.suse.com/1274386	self
https://www.suse.com/security/cve/CVE-2026-71554/	self
https://www.suse.com/security/cve/CVE-2026-71554	external
https://bugzilla.suse.com/1274386	external

JSON

To clipboard

{
  "document": {
    "aggregate_severity": {
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      "text": "moderate"
    },
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        "text": "This update for python-h2 fixes the following issue:\n\n- CVE-2026-71554: duplicate `Host` headers are accepted and forwarded to consuming applications, which can lead to\n  request smuggling (bsc#1274386).\n",
        "title": "Description of the patch"
      },
      {
        "category": "details",
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        "title": "Patchnames"
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      },
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      },
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        }
      ],
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        {
          "category": "general",
          "text": "h2 is a pure-Python implementation of a HTTP/2 protocol stack. Versions up to and including 4.4.0 accept request header blocks containing more than one Host header, and forward every Host header to the consuming application. Where the consumer downgrades HTTP/2 to HTTP/1.1, the resulting request carries two Host header lines, providing a request smuggling primitive. This issue is fixed in version 4.4.1.",
          "title": "CVE description"
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          "url": "https://bugzilla.suse.com/1274386"
        }
      ],
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            "SUSE Linux Enterprise Server 16.0:python313-h2-0:4.2.0-160000.4.1.noarch",
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          ]
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            "version": "3.1"
          },
          "products": [
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          ]
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        }
      ],
      "title": "CVE-2026-71554"
    }
  ]
}

CVE-2026-71554 (GCVE-0-2026-71554)

Vulnerability from cvelistv5 – Published: 2026-08-06 21:46 – Updated: 2026-08-08 02:49

Title

h2: Duplicate Host header could facilitate request smuggling

Summary

h2 is a pure-Python implementation of a HTTP/2 protocol stack. Versions up to and including 4.4.0 accept request header blocks containing more than one Host header, and forward every Host header to the consuming application. Where the consumer downgrades HTTP/2 to HTTP/1.1, the resulting request carries two Host header lines, providing a request smuggling primitive. This issue is fixed in version 4.4.1.

Severity

5.3 (Medium)


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

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-08 02:49 UTC

CWE

CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

Assigner

GitHub_M mitre root Scorecard

References

2 references

URL	Tags
https://github.com/python-hyper/h2/security/advis…	x_refsource_CONFIRM
https://github.com/python-hyper/h2/commit/292a408…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
python-hyper	h2	Affected: < 4.4.1

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-71554",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-08T02:49:21.263516Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-08-08T02:49:30.505Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "h2",
          "vendor": "python-hyper",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 4.4.1"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "h2 is a pure-Python implementation of a HTTP/2 protocol stack. Versions up to and including 4.4.0 accept request header blocks containing more than one Host header, and forward every Host header to the consuming application. Where the consumer downgrades HTTP/2 to HTTP/1.1, the resulting request carries two Host header lines, providing a request smuggling primitive. This issue is fixed in version 4.4.1."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "LOW",
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "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:L",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-444",
              "description": "CWE-444: Inconsistent Interpretation of HTTP Requests (\u0027HTTP Request/Response Smuggling\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-06T21:46:43.057Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/python-hyper/h2/security/advisories/GHSA-6hr6-w5qg-qmwg",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/python-hyper/h2/security/advisories/GHSA-6hr6-w5qg-qmwg"
        },
        {
          "name": "https://github.com/python-hyper/h2/commit/292a40829feefda98c8509dcdbbb4a57af9bd6a6",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/python-hyper/h2/commit/292a40829feefda98c8509dcdbbb4a57af9bd6a6"
        }
      ],
      "source": {
        "advisory": "GHSA-6hr6-w5qg-qmwg",
        "discovery": "UNKNOWN"
      },
      "title": "h2: Duplicate Host header could facilitate request smuggling"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-71554",
    "datePublished": "2026-08-06T21:46:43.057Z",
    "dateReserved": "2026-08-06T21:24:15.376Z",
    "dateUpdated": "2026-08-08T02:49:30.505Z",
    "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.

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.

Action not permitted

SUSE-SU-2026:23563-1

CVE-2026-71554 (GCVE-0-2026-71554)

Tags

Sightings

Nomenclature

Related by attack behaviour