CVE-2026-123863
Node.js is vulnerable to a remote HTTP/2 denial of service via a reachable assertion in Http2Session teardown
A reachable assertion in Node.js HTTP/2 session teardown lets any unauthenticated client abort the server, over both TLS and cleartext. A client can arrange for an Http2Stream that still holds nghttp2-allocated header buffers to outlive its session: the stream is removed from the session's stream set but never detached, so when ~Http2Session() runs the memory accounting is nonzero and the CHECK_EQ(current_nghttp2_memory_, 0) assertion fails, terminating the process. The trigger needs only a default http2 server whose handler responds before the request body has ended, which is typical. It is a variant of CVE-2024-27983 that the earlier fix did not cover, because that fix only detached streams still tracked in the session. This vulnerability affects Node.js 26.x (since 26.9.0) and 24.x (since 24.22.0).
| CWE | CWE-617 |
| Vendor | nodejs |
| Product | node |
| Ecosystems | |
| Industries | Technology |
| Published | Nov 11, 2026 |
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CVSS v3 Breakdown
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H