CVE-2026-123864

Public on 2026-11-11
Modified on 2026-11-11
Description
A re-entrancy flaw in Node.js HTTPS lets an unauthenticated client read memory belonging to other connections, including TLS private keys and other users' requests. TLSWrap::DoWrite() calls ClearOut() directly when asked to write zero bytes; if that write is issued from JavaScript running inside the HTTP parser's on_body callback, ClearOut() decrypts the next TLS record while the parser is still mid-body, re-entering llhttp_execute() and causing a use-after-free and an out-of-bounds heap read. The server then copies that freed or unrelated heap memory into the response for the request body. Triggering it requires a handler that calls res.flushHeaders() before the request body ends and later calls res.end() with a non-empty chunk, and reading the leaked memory requires any ordinary route that echoes or stores a request body. Cleartext node:http is not affected. This vulnerability affects Node.js 26.x, 24.x, and 22.x.
Severity
Important severity
Important
See what this means
CVSS v3 Base Score
7.4
See breakdown

Affected Packages

Platform Package Release Date Advisory Status
Amazon Linux 2023 nodejs No Fix Planned
Amazon Linux 2 - Core nodejs-packaging Not Affected
Amazon Linux 2023 nodejs20 No Fix Planned
Amazon Linux 2023 nodejs22 Pending Fix
Amazon Linux 2023 nodejs24 Pending Fix
Amazon Linux 2027 Preview nodejs24 Pending Fix

CVSS Scores

Score Type Score Vector
Amazon Linux CVSSv3 7.4 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H