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CVE-2026-123863

Node.js is vulnerable to a remote HTTP/2 denial of service via a reachable assertion in Http2Session teardown

No exploitation reported by the sources we read.

  • Published2026-11-11
  • WeaknessCWE-617

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

A reachable assertion in Node.js HTTP/2 session teardown lets any unauthenticated client abort the server, over both TLS and cleartext. A client can arrange for an Http2Stream that still holds nghttp2-allocated header buffers to outlive its session: the stream is removed from the session's stream set but never detached, so when ~Http2Session() runs the memory accounting is nonzero and the CHECK_EQ(current_nghttp2_memory_, 0) assertion fails, terminating the process. The trigger needs only a default http2 server whose handler responds before the request body has ended, which is typical. It is a variant of CVE-2024-27983 that the earlier fix did not cover, because that fix only detached streams still tracked in the session. This vulnerability affects Node.js 26.x (since 26.9.0) and 24.x (since 24.22.0).

Timeline

dates in UTC
  1. 2026-11-1118:16CVE 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
    • ≥ 24.0.0, < 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-2026-123863 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 3.08.22026-11-11
  • CNAweakness (CWE)CWE-6172026-11-11

Identifiers

Technical details

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

Frequently asked questions

What is CVE-2026-123863?

A reachable assertion in Node.js HTTP/2 session teardown lets any unauthenticated client abort the server, over both TLS and cleartext. A client can arrange for an Http2Stream that still holds nghttp2-allocated header buffers to outlive its session: the stream is removed from the session's stream set but never detached, so when ~Http2Session() runs the memory accounting is nonzero and the CHECK_EQ(current_nghttp2_memory_, 0) assertion fails, terminating the process. The trigger needs only a default http2 server whose handler responds before the request body has ended, which is typical. It is a variant of CVE-2024-27983 that the earlier fix did not cover, because that fix only detached streams still tracked in the session. This vulnerability affects Node.js 26.x (since 26.9.0) and 24.x (since 24.22.0).

Is CVE-2026-123863 actively exploited?

Active exploitation of CVE-2026-123863 has not been confirmed.

What is the CVSS score for CVE-2026-123863?

CVE-2026-123863 has a CVSS v3 base score of 8.2 (HIGH severity), with vector string CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H.

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