CVE-2026-21717 Denial of service in node
Attackers can cause denial of service in Node.js applications by triggering predictable hash collisions in V8's string hashing mechanism via crafted JSON input.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-21717?
CVE-2026-21717 is a medium-severity denial of service vulnerability in Nodejs Node.js, published on 30 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A flaw in V8's string hashing mechanism causes integer-like strings to be hashed to their numeric value, making hash collisions trivially predictable. By crafting a request that causes many such collisions in V8's internal string table, an attacker can significantly degrade performance of the Node.js process. The most common trigger is any endpoint that calls `JSON.parse()` on attacker-controlled input, as JSON parsing automatically internalizes short strings into the affected hash table. This vulnerability affects **20.x, 22.x, 24.x, and 25.x**.
Weakness: CWE-328
Which versions are affected by CVE-2026-21717?
2 open source packages ship an affected version, including node and node-min. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
node Bitnami | All versions | 20.20.2, 22.22.2, 24.14.1, 25.8.2 |
node-min Bitnami | All versions | 20.20.2, 22.22.2, 24.14.1, 25.8.2 |
Products include Nodejs Node.js.
How do I fix CVE-2026-21717?
Upgrade node to a fixed version for your release line: 20.20.2, 22.22.2, 24.14.1 or 25.8.2.
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-2026-21717 being exploited?
There is no known exploitation of CVE-2026-21717 in the wild and no public exploit code.
Public exploit code: 1 proofs of concept on GitHub.
Other vulnerabilities in Nodejs Node.js
Sources
Also known as ALPINE-CVE-2026-21717, AZL-81245, BELL-CVE-2026-21717, BIT-node-2026-21717, BIT-node-min-2026-21717, CLEANSTART-2026-UC30604 and 10 more.