Bug 2571842 (CVE-2026-123863)

Summary: CVE-2026-123863 nodejs: Node.js: Denial of Service via improper HTTP/2 session teardown
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in Node.js. An unauthenticated remote attacker can cause a Denial of Service (DoS) by triggering an abnormal server crash during HTTP/2 session termination. By sending a request where the server responds before the request body has finished transmitting, an individual stream can outlive its parent session while retaining allocated memory. This inconsistency triggers an internal check failure during session cleanup, immediately terminating the server process.
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Description OSIDB Bzimport 2026-11-11 18:31:59 UTC 
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).