CVE-2026-22036 Undici has an unbounded decompression chain in HTTP responses on Node.js Fetch API via Content-Encoding leads to resource exhaustion
A malicious server can cause resource exhaustion in Undici via unbounded decompression chains, leading to denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-22036?
CVE-2026-22036 is a medium-severity denial of service vulnerability in Nodejs Undici, published on 14 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Undici is an HTTP/1.1 client for Node.js. Prior to 7.18.0 and 6.23.0, the number of links in the decompression chain is unbounded and the default maxHeaderSize allows a malicious server to insert thousands compression steps leading to high CPU usage and excessive memory allocation. This vulnerability is fixed in 7.18.0 and 6.23.0.
Weakness: CWE-770
Which versions are affected by CVE-2026-22036?
4 open source packages ship an affected version, including undici. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
undici npm | All versions | 6.23.0 |
undici npm | All versions | 6.23.0 |
undici npm | From 7.0.0 | 7.18.2 |
undici npm | From 7.0.0 | 7.18.2 |
Linux distribution packages (1)
nodejs24 openSUSE:Tumbleweed | All versions | 24.13.0-2.1 |
Products include Nodejs Undici.
How do I fix CVE-2026-22036?
Upgrade undici to a fixed version for your release line: 6.23.0 or 7.18.2.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-22036 being exploited?
There is no known exploitation of CVE-2026-22036 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 CLEANSTART-2026-MB67132, CLSA-2026-1775434874, CLSA-2026-1787000958, DEBIAN-CVE-2026-22036, ECHO-8428-9583-4bb5, GHSA-g9mf-h72j-4rw9 and 11 more.