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Fencer Intel
high 8.1

CVE-2026-123864 json

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

published 16h ago modified 15h ago also EUVD-2026-123683

cvss
8.1
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
—
no EPSS score yet
public exploits
0
none known

Summary

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.

Patch / fix

  • nodejs node 22.23.5, 24.22.3, 26.13.1
  • nodejs Alpine 3.22, Alpine 3.21 22.23.5-r0
  • nodejs Alpine 3.24, Alpine 3.23 24.22.3-r0

alpine advisories ALPINE-CVE-2026-123864

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-123864 updated cvss 7.4

nodejs: nodejs: Information disclosure via HTTPS parser re-entrancy

  • Red Hat Hardened Images nodejs25 25.9.0-1.7.hum1, nodejs20 20.20.2-1.3.hum1, nodejs24 24.22.2-0.2.hum1, nodejs26 26.13.0-0.1.1.hum1, nodejs22 22.23.4-2.3.2.3.1.hum1
    affected: workaround, no fix available, no fix planned “Will not fix”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CVSS scores

assigned by version score vector
CNA 3.0 8.1 CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:H

Affected products

  • nodejs node

Classification

Weakness
Technology feeds

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.