CVE-2026-123863: Node.js is vulnerable to a remote HTTP/2 denial of service via a reachable assertion in Http2Session teardown
- Is it exploited?
Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of . If CISA adds it, this page shows it as known exploited.
- How likely is exploitation in the next 30 days?
- 0.5%
EPSS score, percentile 40.5 of all scored records. A probability estimated by FIRST, not a report of exploitation.
- How severe?
- 8.2 High
CVSS v3.0 base score, given by the CNA
- What should I do?
CISA has set no required action, because the vulnerability is not in KEV.
- Which versions are affected?
Affected
- from 24.0.0 to before 24.22.3
- from 25.0.0 to before 26.13.1
Source: CISA KEV 2026.11.10, as of ; FIRST EPSS, as of ; CVE List, as of . About the data.
Description
Node.js is vulnerable to a remote HTTP/2 denial of service via a reachable assertion in Http2Session teardown
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).
Source: CVE List, as of . About the data.
What to do
Advisories and patches
This summary is based on the CVE record as of . Check the vendor's advisory before you act: affected versions and fixes can change.
Affected products and versions
Versions by product, as listed in the CVE record (1 product)
| Status | Versions |
|---|---|
| Affected | from 24.0.0 to before 24.22.3 |
| Affected | from 25.0.0 to before 26.13.1 |
Versions not listed are: unaffected.
Source: CVE List, as of . About the data.
Weakness
CWE-617
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record.
Timeline
| Date | Event |
|---|---|
| CVE record published |