CVE-2026-21863: Malformed Valkey Cluster bus message can lead to Remote DoS

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-02-23 · updated 2026-07-15
Weakness: CWE-125

Description

Valkey is a distributed key-value database. Prior to versions 9.0.2, 8.1.6, 8.0.7, and 7.2.12, a malicious actor with access to the Valkey clusterbus port can send an invalid packet that may cause an out bound read, which might result in the system crashing. The Valkey clusterbus packet processing code does not validate that a clusterbus ping extension packet is located within buffer of the clusterbus packet before attempting to read it. Versions 9.0.2, 8.1.6, 8.0.7, and 7.2.12 fix the issue. As an additional mitigation, don't expose the cluster bus connection directly to end users, and protect the connection with its own network ACLs.

Affected products

valkey-io valkey: before 7.2.12; from 8.0.0 before 8.0.7; from 8.1.0 before 8.1.6; from 9.0.0 before 9.0.2 — fixed in 7.2.12, 8.0.7, 8.1.6, 9.0.2

How to fix

Upgrade to a fixed version: valkey-io valkey 7.2.12, 8.0.7, 8.1.6, 9.0.2. Check the vendor advisory for mitigations.

References

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