# CVE-2026-12151 — undici

> As of 2026-06-17, CVE-2026-12151 is a HIGH-severity vulnerability in undici, CVSS v3.1 7.5. No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-12151 as of 2026-06-17; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-06-17

## What is CVE-2026-12151?

Impact: The undici WebSocket client enforces maxPayloadSize on the cumulative byte count of fragments in a message but does not enforce a limit on the number of fragments. A malicious WebSocket server can stream many small or empty continuation frames that each pass per-frame and cumulative-size validation, collectively causing unbounded memory growth in the client process. The result is memory exhaustion and a denial of service. Affected applications are those using the undici WebSocket client (new WebSocket(...)) or the WebSocketStream API that can be induced to connect to an attacker-controlled or compromised WebSocket endpoint. All releases starting at undici 6.17.0 are affected. Patches: Upgrade to undici >= 6.26.0, >= 7.28.0, or >= 8.5.0. Workarounds: No workaround is available. The fix must be applied through an upgrade.

The record classifies CVE-2026-12151 under weakness classes [CWE-400](https://intel.threadlinqs.com/cwe/CWE-400), [CWE-770](https://intel.threadlinqs.com/cwe/CWE-770). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 110 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 7.5 — HIGH (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 3.8/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-06-17

## Is CVE-2026-12151 being exploited?

It currently carries a trending score of 30 in the Threadlinqs vulnerability feed.

## Affected products and versions

- **undici**: undici

## How to fix CVE-2026-12151

No vendor patch reference has been recorded for CVE-2026-12151 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-12151

No threat campaign in the Threadlinqs corpus currently references CVE-2026-12151, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org. Last verified by Threadlinqs on 2026-06-19.

**Other references**

- [github.com](https://github.com/nodejs/undici/security/advisories/GHSA-vxpw-j846-p89q)
- [cna.openjsf.org](https://cna.openjsf.org/security-advisories.html)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-12151
Full detection coverage and IOCs for threats exploiting CVE-2026-12151 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp