Quick answers
- Is CVE-2026-123866 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-123866 being exploited in the wild.
- How severe is CVE-2026-123866?
- High severity, with a CVSS score of 7.5, published 11 November 2026.
- Which products and versions are affected?
- OpenJS Foundation Node.js 22.x, 24.x, 26.x.
- Is there a fix for CVE-2026-123866?
- Yes: fixed in <UNKNOWN>. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-123866 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-123866?
- Check whether you run OpenJS Foundation Node.js at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- Fixed in: <UNKNOWN>
Technical details
A use-after-free vulnerability in HTTP/2 stream teardown occurs when a stream is destroyed while a write operation is still backpressured (e.g., via RST_STREAM or per-stream timeout), causing freed response buffer memory to be written to the socket. On Node.js 26.x and 24.x, this can be triggered remotely by a peer after the window-size change from v26.9.0 and v24.22.0; on all supported lines it is reachable via application-initiated teardown such as idle timeouts. The attacker gains disclosure of freed or unrelated heap memory, potentially including other connections' response contents.
Affected products
- OpenJS Foundation Node.js 22.x, 24.x, 26.x
Timeline
- 2026-11-11: disclosed