{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-82391",
        "assignerOrgId": "e2e69745-5e70-4e92-8431-deb5529a81ad",
        "state": "PUBLISHED",
        "assignerShortName": "zephyr",
        "dateReserved": "2026-08-28T21:11:46.166Z",
        "datePublished": "2026-11-10T22:07:39.047Z",
        "dateUpdated": "2026-11-10T22:07:39.047Z"
    },
    "containers": {
        "cna": {
            "providerMetadata": {
                "orgId": "e2e69745-5e70-4e92-8431-deb5529a81ad",
                "shortName": "zephyr",
                "dateUpdated": "2026-11-10T22:07:39.047Z"
            },
            "title": "Out-of-bounds write in Zephyr HTTP/2 server static-filesystem handler via corrupted receive-buffer length",
            "descriptions": [
                {
                    "lang": "en",
                    "value": "The HTTP/2 front-end of the Zephyr HTTP server aliased connection receive state as a scratch output. In subsys/net/lib/http/http_server_http2.c, handle_http2_static_fs_resource() passed &client->data_len as the file_size out-parameter of http_server_find_file(). client->data_len is the count of unprocessed bytes remaining in the fixed-size per-connection receive buffer client->buffer[CONFIG_HTTP_SERVER_CLIENT_BUFFER_SIZE] (256 bytes by default), an invariant every frame handler and the socket receive path rely on. Serving any static file therefore replaced that bounded value with the file's on-disk size, and nothing resets it afterwards.\n\nThe defect is reached by an unauthenticated HTTP/2 GET for any file under the web root, in applications that register a static-filesystem resource (HTTP_RESOURCE_TYPE_STATIC_FS) with CONFIG_FILE_SYSTEM=y; CONFIG_HTTP_SERVER_VERSION_2 is enabled by default and no TLS or credentials are required on this path. Once client->data_len exceeds the buffer size, the frame dispatch loop in subsys/net/lib/http/http_server_core.c keeps parsing past the end of the received data, and the peer controls the bytes at client->cursor, so it can choose which fabricated frame the state machine consumes next by appending bytes after its request.\n\nThe inflated length defeats the only guards on the buffer. parse_http_frame_header() and the per-frame handlers read and skip up to a 24-bit frame length beyond the buffer (out-of-bounds read); the compaction memmove(client->buffer, client->cursor, client->data_len) at the end of request handling copies the file-size number of bytes into the 256-byte buffer, overflowing the rest of struct http_client_ctx — including the current_detail/current_stream pointers, the parser_settings function-pointer table and the inactivity_timer work handler — and the adjacent client contexts in static memory; and the subsequent zsock_recv(client->fd, client->buffer + client->data_len, sizeof(client->buffer) - client->data_len, 0) underflows its size argument, writing attacker-supplied data of attacker-chosen length out of bounds.\n\nThe impact is remote memory corruption in the server's single address space: at minimum a crash or hang of the device, and plausibly control-data overwrite leading to code execution. The HTTP/1 and HTTP/3 static-filesystem handlers already used a local variable and are unaffected; the fix makes the HTTP/2 handler use a local size_t file_size as well."
                }
            ],
            "affected": [
                {
                    "vendor": "zephyrproject",
                    "product": "zephyr",
                    "collectionURL": "https://github.com/zephyrproject-rtos/zephyr",
                    "packageName": "zephyr",
                    "defaultStatus": "unaffected",
                    "programFiles": [
                        "subsys/net/lib/http/http_server_http2.c"
                    ],
                    "programRoutines": [
                        {
                            "name": "handle_http2_static_fs_resource"
                        }
                    ],
                    "versions": [
                        {
                            "version": "4.0.0",
                            "status": "affected",
                            "versionType": "semver",
                            "lessThan": "4.3.2"
                        },
                        {
                            "version": "4.4.0",
                            "status": "affected",
                            "versionType": "semver",
                            "lessThan": "4.5.0"
                        }
                    ]
                }
            ],
            "references": [
                {
                    "url": "https://github.com/zephyrproject-rtos/zephyr/commit/4e0a5f38b14dba5891fb558c49a526f9f6a3cc29",
                    "name": "Fix commit",
                    "tags": [
                        "patch"
                    ]
                },
                {
                    "url": "https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-8jrg-wx88-g75j",
                    "name": "GHSA-8jrg-wx88-g75j"
                }
            ],
            "metrics": [
                {
                    "format": "CVSS",
                    "cvssV3_1": {
                        "version": "3.1",
                        "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H",
                        "baseScore": 9.1,
                        "baseSeverity": "CRITICAL"
                    }
                }
            ],
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "lang": "en",
                            "description": "memory-safety",
                            "cweId": "CWE-787",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "x_generator": {
                "engine": "cvelib 1.8.0"
            }
        }
    }
}