CVE-2026-63421 Keystone: `graphql.maxTake` bypass with negative `take`
Attackers can bypass GraphQL take limits using negative values to retrieve excessive records, potentially causing resource exhaustion.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-63421?
CVE-2026-63421 is a high-severity vulnerability in keystonejs keystone, published on 21 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Keystone is a content management system for Node.js. Prior to 6.5.3, the findMany resolver in packages/core/src/lib/core/queries/resolvers.ts compares the signed take argument directly with graphql.maxTake, allowing a remote unauthenticated GraphQL client to provide a negative take value whose magnitude exceeds the configured bound. The bypass also applies to relationship queries and can return more records than the developer intended, potentially exhausting service resources. This issue is fixed in version 6.5.3.
Which versions are affected by CVE-2026-63421?
2 open source packages ship an affected version, including @keystone-6/core.
| Package | Affected | Fixed in |
|---|---|---|
@keystone-6/core npm | All versions | 6.5.3 |
@keystone-6/core npm | All versions | 6.5.3 |
How do I fix CVE-2026-63421?
Upgrade @keystone-6/core to 6.5.3 or later.
Is CVE-2026-63421 being exploited?
There is no known exploitation of CVE-2026-63421 in the wild and no public exploit code.
Sources
Also known as GHSA-cqmq-8755-7xvh.