CVE-2026-62966

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{"affected": [{"affectedData": [{"product": "ESPAsyncWebServer", "vendor": "ESP32Async", "versions": [{"status": "affected", "version": "< 3.11.2"}]}], "source": "security-advisories@github.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "ESPAsyncWebServer is an asynchronous HTTP and WebSocket server library for ESP32, ESP8266, RP2040 and RP2350. Prior to version 3.11.2, the multipart parser in `src/WebRequest.cpp` frees `_itemBuffer` and sets it to NULL when `BOUNDARY_OR_DATA` matches the closing boundary of a file part, before confirming the following terminator, while leaving `_itemIsFile` true. If the next byte is neither the final closing dashes nor a clean CRLF, the `DASH3_OR_RETURN2` or `EXPECT_FEED2` rewind branch re-injects provisionally consumed bytes through `itemWriteByte`. Because `_itemIsFile` remains true, `_itemBuffer`[`_itemBufferIndex`++] writes through a null pointer. On ESP32 this causes a `StoreProhibited` exception, panic and device reboot, producing remote denial of service. A route with a non-trivial body/upload handler, such as a file-upload or web-OTA endpoint, must be present. This issue is fixed in version 3.11.2."}], "id": "CVE-2026-62966", "lastModified": "2026-11-06T19:17:54.740", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 7.5, "baseSeverity": "HIGH", "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:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 3.6, "source": "security-advisories@github.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-62966", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-11-06T18:20:37.577657Z", "version": "2.0.3"}}]}, "published": "2026-10-30T21:17:15.137", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/ESP32Async/ESPAsyncWebServer/commit/4efbd35e597d91f01749f2d4a14bb78fba8ea02e"}, {"source": "security-advisories@github.com", "url": "https://github.com/ESP32Async/ESPAsyncWebServer/security/advisories/GHSA-8m8p-vhxc-jmjw"}, {"source": "security-advisories@github.com", "url": "https://github.com/ESP32Async/ESPAsyncWebServer/tree/v3.11.2"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Deferred", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-476"}, {"lang": "en", "value": "CWE-672"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,3.11.2)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "ESPAsyncWebServer", "source": "cna", "vendor": "ESP32Async"}, "product": "espasyncwebserver", "vendor": "esp32async"}], "created": "2026-10-30T22:45:14.056064+00:00", "updated": "2026-10-30T22:45:14.533727+00:00", "vendors": ["esp32async", "esp32async$PRODUCT$espasyncwebserver"]}