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CVE-2026-123864

Node.js is vulnerable to cross-connection memory disclosure via TLS write re-entrancy in the HTTPS request parser

No exploitation reported by the sources we read.

  • Published2026-11-11
  • WeaknessCWE-416

Am I affected?

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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.

Timeline

dates in UTC
  1. 2026-11-1118:17CVE publishedCNA

Versions per branch

Products declared by the CNA

As openjs, the CNA that assigned this CVE, declared them in the CVE record; versions as written. NVD lists no product for this CVE yet: this is the only product data so far.

  • nodejs nodeother versions: not affected
    Affected
    • ≥ 0.0.0, < 22.23.5fixed in 22.23.5semver
    • ≥ 23.0.0, < 24.22.3fixed in 24.22.3semver
    • ≥ 25.0.0, < 26.13.1fixed in 26.13.1semver

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-11-11

Neither OSV.dev nor the vendor advisories we read list affected versions for CVE-2026-123864 yet.

Full record on NVD

Fix

No fix published by the sources we read yet. NVD record

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Metasploit modules
none listed
Metasploit Framework

Sources

  • NVDCVE recordread 2026-11-11
  • CNACVSS 3.08.12026-11-11
  • CNAweakness (CWE)CWE-4162026-11-11

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:H
Published
2026-11-11
Last Modified
2026-11-11
NVD status
Received

Frequently asked questions

What is CVE-2026-123864?

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.

Is CVE-2026-123864 actively exploited?

Active exploitation of CVE-2026-123864 has not been confirmed.

What is the CVSS score for CVE-2026-123864?

CVE-2026-123864 has a CVSS v3 base score of 8.1 (HIGH severity), with vector string CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:H.

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