CVE-2026-123864
Publication date 12 November 2026
Last updated 13 November 2026
Ubuntu priority
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.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| nodejs | 26.10 stonking |
Needs evaluation
|
| 26.04 LTS resolute |
Needs evaluation
|
|
| 24.04 LTS noble |
Needs evaluation
|
|
| 22.04 LTS jammy |
Needs evaluation
|
|
| 20.04 LTS focal |
Needs evaluation
|
|
| 18.04 LTS bionic |
Needs evaluation
|
|
| 16.04 LTS xenial |
Needs evaluation
|
|
| 14.04 LTS trusty |
Needs evaluation
|
Severity score breakdown
CVSS version: CVSS v3.0
Base score
8.1 · High
Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:H
References
Other references
- https://www.cve.org/CVERecord?id=CVE-2026-123864
- https://nodejs.org/en/blog/vulnerability/november-2026-security-releases#https-a-zero-length-tls-write-re-enters-llhttp_execute-and-the-server-copies-its-own-heap-into-the-request-body-cve-2026-123864---high
- https://cna.openjsf.org/security-advisories.html
- https://nodejs.org/en/blog/vulnerability/november-2026-security-releases