CVE-2026-21863

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.6%, top 57% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 7.5Exploit: None knownExposed: 0

A fix is available — apply it.

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 v3
7.5
EG Score
7.5(medium)
EG Risk
49(Track)
EG Risk 49/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity75% × 45%
Exploitation1% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
43%
KEV
Not listed

Published

February 23, 2026

Last Modified

July 15, 2026

Advisory Details (7)

Auto-updated Jul 2, 2026
Patch available. Sources: redhat, github.
redhat Patch Available
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-21863.json
redhat Patch Available

2442026 – (CVE-2026-21863) CVE-2026-21863 valkey: Valkey: Denial of Service via invalid clusterbus packet

Affected: Red Hat Enterprise Linux 10

https://bugzilla.redhat.com/show_bug.cgi?id=2442026
redhat Patch Available

cve-details

https://access.redhat.com/security/cve/CVE-2026-21863
redhat Patch Available

Affected: Red Hat Enterprise Linux 10.0 Extended Update Support.

https://access.redhat.com/errata/RHSA-2026:5445
redhat Patch Available

Affected: Red Hat Enterprise Linux 9.

https://access.redhat.com/errata/RHSA-2026:3507
redhat Patch Available

Affected: Red Hat Enterprise Linux 10.

https://access.redhat.com/errata/RHSA-2026:3443
github Patch Available

Remote DoS with malformed Valkey Cluster bus message · Advisory · valkey-io/valkey · GitHub

https://github.com/valkey-io/valkey/security/advisories/GHSA-c677-q3wr-gggq

Vendor Advisories for CVE-2026-21863(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(5)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuvalkey-tools (8.1.6+dfsg1-0ubuntu0.1) @ questing2026-06-30ubuntu
redhatvalkey-main-9.0.3-1.2.hum12026-04-17redhat
redhatvalkey-0:8.0.7-1.el10_02026-03-23redhat
redhatvalkey-0:8.0.7-1.el9_72026-03-02redhat
redhatvalkey-0:8.0.7-1.el10_12026-02-26redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(5)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 7× in last 7d / 45× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-08-01 04:15 UTCEPSS rescore
  2. 2026-07-30 01:30 UTCEPSS rescore
  3. 2026-07-27 14:13 UTCEPSS rescore
  4. 2026-07-26 14:54 UTCEPSS rescore
  5. 2026-07-26 14:54 UTCEPSS rescore
  6. 2026-07-25 14:17 UTCEPSS rescore
  7. 2026-07-25 14:17 UTCEPSS rescore
  8. 2026-07-24 14:17 UTCEPSS rescore
  9. 2026-07-23 14:18 UTCEPSS rescore
  10. 2026-07-23 14:18 UTCEPSS rescore
  11. 2026-07-23 03:06 UTCEG score recompute
  12. 2026-07-22 14:08 UTCEPSS rescore
  13. 2026-07-21 15:24 UTCEPSS rescore
  14. 2026-07-21 15:24 UTCEPSS rescore
  15. 2026-07-20 17:08 UTCEPSS rescore
  16. 2026-07-19 14:31 UTCEPSS rescore
  17. 2026-07-19 14:31 UTCEPSS rescore
  18. 2026-07-19 02:29 UTCEPSS rescore
  19. 2026-07-19 02:28 UTCEPSS rescore
  20. 2026-07-18 10:04 UTCEPSS rescore
  21. 2026-07-18 10:04 UTCEPSS rescore
  22. 2026-07-18 06:59 UTCOSV refresh
  23. 2026-07-16 17:03 UTCEPSS rescore
  24. 2026-07-16 17:03 UTCEPSS rescore
  25. 2026-07-15 16:57 UTCEPSS rescore
Show 26 more
  1. 2026-07-15 16:57 UTCEPSS rescore
  2. 2026-07-15 02:00 UTCEPSS rescore
  3. 2026-07-15 02:00 UTCEPSS rescore
  4. 2026-07-13 22:30 UTCEPSS rescore
  5. 2026-07-13 06:13 UTCEPSS rescore
  6. 2026-07-13 06:13 UTCEPSS rescore
  7. 2026-07-12 05:46 UTCEPSS rescore
  8. 2026-07-12 05:46 UTCEPSS rescore
  9. 2026-07-11 08:27 UTCEPSS rescore
  10. 2026-07-09 19:10 UTCEPSS rescore
  11. 2026-07-08 15:15 UTCEPSS rescore
  12. 2026-07-08 15:15 UTCEPSS rescore
  13. 2026-07-07 13:46 UTCEPSS rescore
  14. 2026-07-06 16:27 UTCEPSS rescore
  15. 2026-07-06 16:27 UTCEPSS rescore
  16. 2026-07-06 02:23 UTCEPSS rescore
  17. 2026-07-06 02:23 UTCEPSS rescore
  18. 2026-07-05 02:30 UTCEPSS rescore
  19. 2026-07-04 06:31 UTCEPSS rescore
  20. 2026-07-04 06:31 UTCEPSS rescore
  21. 2026-07-01 15:06 UTCEPSS rescore
  22. 2026-07-01 15:06 UTCEPSS rescore
  23. 2026-06-30 23:22 UTCEPSS rescore
  24. 2026-06-30 04:41 UTCEG score recompute
  25. 2026-06-30 04:41 UTCVendor advisory
  26. 2026-06-30 04:31 UTCNVD updatefirst tracked

Frequently asked(5)

What is CVE-2026-21863?
CVE-2026-21863 is a high vulnerability published on February 23, 2026. 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…
When was CVE-2026-21863 disclosed?
CVE-2026-21863 was first published in the National Vulnerability Database on February 23, 2026, with the most recent update on July 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-21863 actively exploited?
CVE-2026-21863 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 57.0% of all scored CVEs.
What is the CVSS score of CVE-2026-21863?
CVE-2026-21863 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-21863?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-21863, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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