脆弱性の一覧へ戻る
編集部の見出し：Zephyr：HTTP/2 CONTINUATION で NULL ポインタ書き込み（7.5）
NVD の情報
The HTTP/2 server in subsys/net/lib/http/http_server_http2.c clears the connection's stream binding at the start of every frame. handle_http_frame_header() executed client->current_stream = NULL unconditionally, but a CONTINUATION frame does not open a new stream and enter_http_frame_continuation_state() never re-bound one, so the rest of the header block was processed with client->current_stream unset. Two paths then write through the NULL pointer. A request for an unregistered resource, or a method the matched resource does not support, is answered by send_http2_404() or send_http2_405(), and both call send_headers_frame(), which unconditionally sets client->current_stream->headers_sent = true. A POST, PUT or PATCH to a registered dynamic resource reaches handle_http2_dynamic_resource(), which unlike its siblings (handle_http2_static_resource(), dynamic_get_del_opts_req_v2(), dynamic_post_put_req_v2()) had no client->current_stream == NULL guard, and stores through the pointer with client->current_stream->current_detail = dynamic_detail. Any peer that can reach the server can trigger this without authentication or prior state. A single stray CONTINUATION frame with END_HEADERS set, sent right after the client preface and requesting any unregistered path, is enough, because nothing rejected a CONTINUATION that no HEADERS frame had opened. A legitimate split header block (a HEADERS frame with END_HEADERS clear whose payload ends on a header-field boundary, then a CONTINUATION with END_HEADERS set) reaches the same state. The in-tree test test_http2_post_headers_with_continuation() did not catch this because it splits the header block mid field, which takes the handle_incomplete_http_header() shortcut that keeps the stream bound. The result is a write to a fixed low address (a small offset into struct http2_stream_ctx), which faults on mainstream targets (flash/vector-table region on Cortex-M, or a trap under MPU/MMU null-pointer detection), and the default fatal-error handler halts the system. Impact is an unauthenticated, remotely triggerable denial of service against any device running the HTTP/2 server: the 404 path needs no particular resource to be registered, and HTTP/2 is built into CONFIG_HTTP_SERVER with cleartext h2c accepted, so TLS does not prevent it. Neither the target address nor the written value is attacker-controlled, so there is no confidentiality or integrity impact. Applications built without CONFIG_HTTP_SERVER are not affected.
- 公開日
- 2026-11-06
- 最終更新（NVD）
- 2026-11-06
- NVD の状態
- Awaiting Analysis
- 脆弱性の種類
- CWE-476
深刻度（CVSS）
- 7.5 HighCVSS 3.1／副／評価：vulnerabilities@zephyrproject.org
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
悪用の状況
CISA KEV には掲載されていません（掲載されていないことは、悪用されていないことの証明ではありません）。
解消方法
- 解消方法の情報なし
「NVD の条件から推定」は、NVD が影響ありとする版の上限から読み取ったもので、修正版とは限りません。「解消方法の情報なし」は、修正が無いという意味ではありません。必ずベンダーの公告で確認してください。
編集部の記載（レポート掲載時）
レポートの編集部がベンダー公告などから転記した内容です。検証済みの値ではないため、必ず出典で確認してください。
2026-11-07 のレポートZephyr：HTTP/2 CONTINUATION で NULL ポインタ書き込み（7.5）
NVD 一覧の記載。
参照（NVD）
NVD から取得：2026-11-06T17:50:21.209Z
This product uses the NVD API but is not endorsed or certified by the NVD.
悪用の確認情報は CISA Known Exploited Vulnerabilities Catalog（NVD 経由で取得）によります。EPSS は FIRST（www.first.org/epss）によります。