Cap'n Proto has an integer overflow in KJ-HTTP

{
  "id": "38e2f7f606d1d234500a6b1a65d7d9f6685ec7db5bc919a93cea0922a42c7b97",
  "url": "https://osv.dev/vulnerability/CVE-2026-32239",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Cap'n Proto has an integer overflow in KJ-HTTP",
    "summary": "Cap'n Proto is a data interchange format and capability-based RPC system. Prior to 1.4.0, a negative Content-Length value was converted to unsigned, treating it as an impossibly large length instead. In theory, this bug could enable HTTP request/response smuggling. This vulnerability is fixed in 1.4.0.",
    "evidence": "osv:CVE-2026-32239",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-32239",
      "aliases": [
        "CVE-2026-32239",
        "GHSA-qjx3-pp3m-9jpm"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/capnproto/capnproto",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "8b892a8a11a632f5d52b877a49728808a142379a"
                },
                {
                  "fixed": "2744b3c012b4aa3c31cefb61ec656829fa5c0e36"
                },
                {
                  "fixed": "e929f0ba7901a6b8f4b5ba9a4db00af43288cbb0"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:capnproto:capnproto:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.4.0"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "2744b3c012b4aa3c31cefb61ec656829fa5c0e36"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "e929f0ba7901a6b8f4b5ba9a4db00af43288cbb0"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-32239.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:38.520862403Z",
      "provider": "osv",
      "references": [
        "https://capnproto.org/capnproto-c++-1.4.0.tar.gz",
        "https://capnproto.org/capnproto-c++-win32-1.4.0.zip",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/32xxx/CVE-2026-32239.json",
        "https://github.com/capnproto/capnproto/security/advisories/GHSA-qjx3-pp3m-9jpm",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-32239",
        "https://github.com/capnproto/capnproto/commit/2744b3c012b4aa3c31cefb61ec656829fa5c0e36",
        "https://github.com/capnproto/capnproto/commit/e929f0ba7901a6b8f4b5ba9a4db00af43288cbb0"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-190",
          "CWE-444"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/32xxx/CVE-2026-32239.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-32239",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 505592,
  "published_at": "2026-03-12T19:33:25.052+00:00"
}