CVE-2026-1528 undici is vulnerable to Malicious WebSocket 64-bit length overflows undici parser and crashes the client
A malicious server can crash the undici client by sending a WebSocket frame with an excessively large 64-bit length, causing an integer overflow and fatal error.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-1528?
CVE-2026-1528 is a high-severity vulnerability in Nodejs Undici, published on 12 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
ImpactA server can reply with a WebSocket frame using the 64-bit length form and an extremely large length. undici's ByteParser overflows internal math, ends up in an invalid state, and throws a fatal TypeError that terminates the process.
Patches
Patched in the undici version v7.24.0 and v6.24.0. Users should upgrade to this version or later.
Which versions are affected by CVE-2026-1528?
4 open source packages ship an affected version, including undici. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
undici npm | From 6.0.0 | 6.24.0 |
undici npm | From 6.0.0 | 6.24.0 |
undici npm | From 7.0.0 | 7.24.0 |
undici npm | From 7.0.0 | 7.24.0 |
Products include Nodejs Undici.
How do I fix CVE-2026-1528?
Upgrade undici to a fixed version for your release line: 6.24.0 or 7.24.0.
Is CVE-2026-1528 being exploited?
There is no known exploitation of CVE-2026-1528 in the wild and no public exploit code.
Other vulnerabilities in Nodejs Undici
- CVE-2026-109855 undici WebSocket client vulnerable to Denial of Service via failed HTTP/2 handshake
- CVE-2026-109869 undici vulnerable to Denial of Service via unhandled error on excessive content-encodings
- CVE-2026-87018 undici vulnerable to Denial of Service via TLS 1.2 certificate-changing renegotiation
- CVE-2026-19534 undici vulnerable to Denial of Service via unrequested WebSocket subprotocol
- CVE-2026-12151 undici WebSocket client vulnerable to denial of service via fragment count bypass
Sources
Also known as BELL-CVE-2026-1528, CLEANSTART-2026-TJ00252, CLEANSTART-2026-ZX81460, DEBIAN-CVE-2026-1528, ECHO-a34f-8d81-b926, GHSA-f269-vfmq-vjvj and 12 more.