# CVE-2026-109932: undici WebSocket client vulnerable to Denial of Service via unbounded automatic PONG buffering

> A malicious WebSocket server can exhaust memory in the undici library by flooding PING frames, causing a denial of service.

- **Severity:** Medium 5.9 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Oct 2026
- **Updated:** 16 Oct 2026
- **Also known as:** CLEANSTART-2026-ME95342, DEBIAN-CVE-2026-109932, ECHO-eedf-2067-3e77, GHSA-9fm3-97px-rjf6, UBUNTU-CVE-2026-109932

## What is CVE-2026-109932?

CVE-2026-109932 is a medium-severity denial of service vulnerability in Nodejs Undici, published on 15 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

undici is an HTTP client library for Node.js. In versions 5.15.0 through 6.29.0, 7.0.0 through 7.30.0, and 8.0.0 through 8.12.1, its WebSocket client, including the bundled WebSocket exposed by Node.js, can be driven to exhaust process memory by a malicious or compromised WebSocket server. For every PING frame received, the client automatically writes a PONG response and ignores the backpressure signal from the socket write, so a server that streams small PING frames while never reading the client's PONGs makes the outbound write queue and heap grow without bound until the Node.js process runs out of memory and terminates. The attack is remote and unauthenticated, needs only a normal WebSocket connection, and is asymmetric, since small inbound PINGs produce a much larger retained outbound queue, with availability the only impact. The issue is fixed in undici 6.29.1, 7.30.1, and 8.12.2, which pause WebSocket frame parsing when the automatic PONG response hits socket backpressure and resume on drain, bounding the outbound queue, and users should upgrade to one of those versions or later. There is no workaround.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling), CWE-405 (Asymmetric Resource Consumption (Amplification)), CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-109932?

6 open source packages ship an affected version, including undici. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `undici` | npm | From 5.15.0 | 6.29.1 |
| `undici` | npm | From 5.15.0 | 6.29.1 |
| `undici` | npm | From 7.0.0 | 7.30.1 |
| `undici` | npm | From 7.0.0 | 7.30.1 |
| `undici` | npm | From 8.0.0 | 8.12.2 |
| `undici` | npm | From 8.0.0 | 8.12.2 |

Products: Nodejs Undici.

## How do I fix CVE-2026-109932?

Upgrade undici to a fixed version for your release line: 6.29.1, 7.30.1 or 8.12.2.

## Is CVE-2026-109932 being exploited?

There is no known exploitation of CVE-2026-109932 in the wild and no public exploit code.

## Other vulnerabilities in Nodejs Undici

- [CVE-2026-109855](https://insights.sbomify.com/CVE-2026-109855/): undici WebSocket client vulnerable to Denial of Service via failed HTTP/2 handshake (high 7.5)
- [CVE-2026-109869](https://insights.sbomify.com/CVE-2026-109869/): undici vulnerable to Denial of Service via unhandled error on excessive content-encodings (high 7.5)
- [CVE-2026-87018](https://insights.sbomify.com/CVE-2026-87018/): undici vulnerable to Denial of Service via TLS 1.2 certificate-changing renegotiation (high 7.5)
- [CVE-2026-19534](https://insights.sbomify.com/CVE-2026-19534/): undici vulnerable to Denial of Service via unrequested WebSocket subprotocol (high 7.5)
- [CVE-2026-12151](https://insights.sbomify.com/CVE-2026-12151/): undici WebSocket client vulnerable to denial of service via fragment count bypass (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-109932 and fix it if it is affected.

What it is: CVE-2026-109932 is a medium-severity denial of service vulnerability in Nodejs Undici, published on 15 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-109932 in the wild and no public exploit code.

Affected packages and fixed versions:
- undici (npm): affected from 5.15.0; fixed in 6.29.1
- undici (npm): affected from 5.15.0; fixed in 6.29.1
- undici (npm): affected from 7.0.0; fixed in 7.30.1
- undici (npm): affected from 7.0.0; fixed in 7.30.1
- undici (npm): affected from 8.0.0; fixed in 8.12.2
- undici (npm): affected from 8.0.0; fixed in 8.12.2

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-109932/ (Markdown: https://insights.sbomify.com/CVE-2026-109932/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-109932
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-109932
- OSV: https://osv.dev/vulnerability/CVE-2026-109932

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-109932/
Summaries are generated and may contain mistakes; the official description above is the record.