Bug 2571844 (CVE-2026-123866)

Summary: CVE-2026-123866 nodejs: Node.js: Information disclosure via use-after-free during HTTP/2 stream teardown
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: high    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in Node.js. A use-after-free vulnerability in the HTTP/2 stream handling mechanism allows for information disclosure. When a stream is terminated while outgoing data is delayed, the server frees the response buffer prematurely while continuing to reference it. A remote attacker can exploit this condition to cause the server to transmit unrelated memory from the heap, potentially exposing sensitive data belonging to other user connections.
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Description OSIDB Bzimport 2026-11-11 18:32:05 UTC 
A use-after-free in Node.js HTTP/2 stream teardown can leak response memory, including the contents of other connections' response buffers, to a peer. When a stream is torn down while a write is still backpressured, for example by a peer RST_STREAM or by the server's own per-stream timeout destroying the stream, the stream's response buffer is freed but a reference to it is still used, so freed or unrelated heap memory is written to the socket instead of the intended response. On Node.js 26.x and 24.x the teardown can be driven purely by a remote peer once the window-size change from 26.9.0 and 24.22.0 is present, and on all supported lines the same defect is reachable through an application-initiated teardown such as a per-stream idle timeout. This vulnerability affects Node.js 26.x, 24.x, and 22.x.