FKIE_CVE-2026-33555

Vulnerability from fkie_nvd - Published: 2026-04-13 17:16 - Updated: 2026-04-22 19:17
Severity ?
4.0 (Medium) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N
Summary
An issue was discovered in HAProxy before 3.3.6. The HTTP/3 parser does not check that the received body length matches a previously announced content-length when the stream is closed via a frame with an empty payload. This can cause desynchronization issues with the backend server and could be used for request smuggling. The earliest affected version is 2.6.
References
cve@mitre.orghttps://github.com/haproxy/haproxy/commit/05a295441c621089ffa4318daf0dbca2dd756a84
cve@mitre.orghttps://r3verii.github.io/cve/2026/04/14/haproxy-h3-standalone-fin-smuggling.html
cve@mitre.orghttps://www.haproxy.com/documentation/haproxy-aloha/changelog/
cve@mitre.orghttps://www.haproxy.org
cve@mitre.orghttps://www.mail-archive.com/haproxy@formilux.org/msg46752.html
134c704f-9b21-4f2e-91b3-4a467353bcc0https://r3verii.github.io/cve/2026/04/14/haproxy-h3-standalone-fin-smuggling.html
Impacted products
Vendor Product Version
To clipboard 

{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "An issue was discovered in HAProxy before 3.3.6. The HTTP/3 parser does not check that the received body length matches a previously announced content-length when the stream is closed via a frame with an empty payload. This can cause desynchronization issues with the backend server and could be used for request smuggling. The earliest affected version is 2.6."
    }
  ],
  "id": "CVE-2026-33555",
  "lastModified": "2026-04-22T19:17:02.273",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 4.0,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 1.4,
        "source": "cve@mitre.org",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-04-13T17:16:28.237",
  "references": [
    {
      "source": "cve@mitre.org",
      "url": "https://github.com/haproxy/haproxy/commit/05a295441c621089ffa4318daf0dbca2dd756a84"
    },
    {
      "source": "cve@mitre.org",
      "url": "https://r3verii.github.io/cve/2026/04/14/haproxy-h3-standalone-fin-smuggling.html"
    },
    {
      "source": "cve@mitre.org",
      "url": "https://www.haproxy.com/documentation/haproxy-aloha/changelog/"
    },
    {
      "source": "cve@mitre.org",
      "url": "https://www.haproxy.org"
    },
    {
      "source": "cve@mitre.org",
      "url": "https://www.mail-archive.com/haproxy@formilux.org/msg46752.html"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "url": "https://r3verii.github.io/cve/2026/04/14/haproxy-h3-standalone-fin-smuggling.html"
    }
  ],
  "sourceIdentifier": "cve@mitre.org",
  "vulnStatus": "Awaiting Analysis",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-130"
        }
      ],
      "source": "cve@mitre.org",
      "type": "Secondary"
    }
  ]
}


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