{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "3.11.1"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "b928de7cbd7debcd6266ece6a6c46f10a86d3a6f"
            },
            {
              "fixed": "d6aa7daf0823a41966b1841826cff015237d6e42"
            }
          ],
          "repo": "https://github.com/esp32async/espasyncwebserver",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-4phx-fcj6-46r4"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-190"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54571.json"
  },
  "details": "ESPAsyncWebServer is an asynchronous HTTP and WebSocket server library for ESP32, ESP8266, RP2040 and RP2350. Prior to 3.11.1, the multipart/form-data parser in src/WebRequest.cpp stores _boundaryPosition as an 8-bit value while _parseMultipartPostByte processes the boundary. A remote request containing an exactly 256-byte multipart boundary wraps _boundaryPosition from 255 to zero, prevents the boundary parsing loop from terminating, consumes excessive CPU, and triggers a FreeRTOS watchdog reset on affected ESP32 or ESP8266 devices. This issue is fixed in version 3.11.1.",
  "id": "CVE-2026-54571",
  "modified": "2026-09-19T03:30:49.965941559Z",
  "published": "2026-09-17T18:28:26.977Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/ESP32Async/ESPAsyncWebServer/releases/tag/v3.11.1"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54571.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/ESP32Async/ESPAsyncWebServer/security/advisories/GHSA-4phx-fcj6-46r4"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-54571"
    },
    {
      "type": "FIX",
      "url": "https://github.com/ESP32Async/ESPAsyncWebServer/commit/b928de7cbd7debcd6266ece6a6c46f10a86d3a6f"
    },
    {
      "type": "FIX",
      "url": "https://github.com/ESP32Async/ESPAsyncWebServer/pull/445"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "ESPAsyncWebServer: Integer overflow in multipart boundary parser causes denial of service"
}