CVE-2026-21863
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.76%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 0.76% probability · 53th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-125
- Affected
- lfprojects/valkey
- Source
- security-advisories@github.com
References
- https://github.com/valkey-io/valkey/security/advisories/GHSA-c677-q3wr-gggqVendor Advisory
- https://access.redhat.com/errata/RHSA-2026:3443
- https://access.redhat.com/errata/RHSA-2026:3507
- https://access.redhat.com/errata/RHSA-2026:5445
- https://access.redhat.com/errata/RHSA-2026:8753
- https://access.redhat.com/security/cve/CVE-2026-21863
- https://bugzilla.redhat.com/show_bug.cgi?id=2442026
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-21863.json
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.