CVE-2026-21863
Malformed Valkey Cluster bus message can lead to Remote DoS
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.
How to fix CVE-2026-21863
To remediate CVE-2026-21863, upgrade the affected package to a fixed version below.
- —upgrade to 7.2.12-r0 or later
- —upgrade to 7.2.12 or later
- —upgrade to 7.3.6+ds-2 or later
- —upgrade to 5:7.0.15-1~deb12u7 or later
- —upgrade to 8.1.1+dfsg1-3+deb13u2 or later
Is CVE-2026-21863 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (5)
- from 0, < 7.2.12-r0
- from 0, < 7.2.12, >= 8.0.0, < 8.0.7, >= 8.1.0, < 8.1.6, >= 9.0.0, < 9.0.2
- from 0, < 7.3.6+ds-2
- from 0, < 5:7.0.15-1~deb12u7
- from 0, < 8.1.1+dfsg1-3+deb13u2
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | HIGH7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |