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CVE-2026-123864VulnerabilityPublished Updated

Nodejs: A re-entrancy flaw

Affects nodejsSource GCVE Database

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Authoritative record:CVE-2026-123864· High 8.1

Not known to be exploited · CVSS 8.1 High.

Data as of 13 Nov 2026, 22:04 UTC

CVSS 3.0 base score
8.1High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (openjs)CVSS 3.08.1
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 11 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
Ubuntu 26.10nodejspkg:deb/ubuntu/nodejs?arch=source&distro=stonkingOther threatsAffected
  • 22.22.1+dfsg+~cs22.19.15-1ubuntu1 – 24.19.0+dfsg+~cs24.13.3-1ubuntu1
4 affected builds
Fixed in–
Ubuntu 26.04 LTSnodejspkg:deb/ubuntu/nodejs?arch=source&distro=resoluteOther threatsAffected
  • 20.19.4+dfsg-1 – 22.22.1+dfsg+~cs22.19.15-1ubuntu1
6 affected builds
Fixed in–
Ubuntu 24.04 LTSnodejspkg:deb/ubuntu/nodejs?arch=source&distro=nobleOther threatsAffected
  • 18.13.0+dfsg1-1ubuntu2 – 18.19.1+dfsg-6ubuntu5
5 affected builds
Fixed in–
Ubuntu Pro 22.04 LTSnodejspkg:deb/ubuntu/nodejs?arch=source&distro=esm-apps/jammyOther threatsAffected
  • 12.22.5~dfsg-5ubuntu1 – 12.22.9~dfsg-1ubuntu3.6+esm2
12 affected builds
Fixed in–
Ubuntu Pro 20.04 LTSnodejspkg:deb/ubuntu/nodejs?arch=source&distro=esm-apps/focalOther threatsAffected
  • 10.15.2~dfsg-2ubuntu1 – 10.19.0~dfsg-3ubuntu1.6+esm2
10 affected builds
Fixed in–
Ubuntu Pro 18.04 LTSnodejspkg:deb/ubuntu/nodejs?arch=source&distro=esm-apps/bionicOther threatsAffected
  • 6.11.4~dfsg-1ubuntu1 – 8.10.0~dfsg-2ubuntu0.4+esm6
15 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

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.

References

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