CVE-2026-55678

MEDIUMPre-NVD 6.96.9—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.9 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 68% 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
Elevated
6.9EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.9Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Arc is an open, SQL-native time-series database for telemetry. From 26.02.1 until 26.06.2, Arc Enterprise clustering accepts cluster join requests without authentication when cluster.enabled is true but cluster.shared_secret is not configured. The defaults in internal/config/config.go set cluster.enabled to false, cluster.cluster_name to arc-cluster, cluster.coordinator_addr to :9100, cluster.shared_secret to an empty value, and cluster.tls_enabled to false, while cmd/arc/main.go requires cluster.shared_secret only when cluster.replication_enabled is true. JoinRequest in internal/cluster/protocol/messages.go accepts attacker-controlled node_id, role, raft_addr, api_addr, and coord_addr values, plus optional auth_nonce, auth_timestamp, and auth_hmac fields. The join path in internal/cluster/coordinator.go validates HMAC authentication only when the configured shared secret is non-empty and otherwise proceeds after only the cluster-name check. An accepted node is marked healthy, added as a Raft voter or registered locally, and becomes available through internal/cluster/registry.go to the routing logic in internal/cluster/router.go. The forwardRequest path in internal/cluster/router.go builds its target from node.APIAddress and copies Authorization and x-api-key headers with the request, so a rogue node selected for a forwarded query or write can receive authentication headers, request bodies, database and measurement names, and operational metadata. Heartbeat in internal/cluster/protocol/messages.go also lacks HMAC fields, and internal/cluster/coordinator.go updates node state from supplied node_id and state values without authentication. An unauthenticated network attacker who can reach the coordinator port and knows the cluster name can therefore become a trusted cluster node, mutate cluster membership, be submitted as a Raft voter, intercept topology-dependent forwarded requests, divert or forge operations, and blackhole or delay traffic. The default standalone configuration is not reachable because cluster.enabled is false, but Enterprise cluster deployments with clustering enabled and no shared secret are affected. This issue is fixed in version 26.06.2.

CVSS v3
6.9
EG Score
6.9(medium)
EG Risk
62(Attend)
EG Risk 62/100SSVC: Attend

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
Severity69% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
0%
EPSS %ILE
33%
KEV
Not listed

Published

August 28, 2026

Last Modified

September 9, 2026

Advisory Details (4)

Auto-updated Aug 28, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_commit, github_pr, github_release.
github Patch Available🟡 PoC Available

Unauthenticated cluster node admission when `cluster.shared_secret` is unset · Advisory · Basekick-Labs/arc · GitHub

https://github.com/Basekick-Labs/arc/security/advisories/GHSA-p378-jp5r-gpgw
github_release Patch Available

Arc 26.06.2

Patch available: Basekick-Labs/arc v26.06.2

https://github.com/Basekick-Labs/arc/releases/tag/v26.06.2
github_pr

fix(cluster): require shared secret for clustering, authenticate heartbeats (GHSA-p378-jp5r-gpgw)

Fix merged in Basekick-Labs/arc PR #505 on 2026-06-15 — awaiting tagged release

https://github.com/Basekick-Labs/arc/pull/505
github_commit

commit 38402ad2ebdd (Basekick-Labs/arc)

Fix landed in Basekick-Labs/arc commit 38402ad2ebdd — awaiting tagged release

https://github.com/Basekick-Labs/arc/commit/38402ad2ebddd32c15bf4a0fc9c22c920e5685df

Vendor Advisories for CVE-2026-55678(1)

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

Affected Packages

(1 across 1 ecosystem)
Go(1)
PackageVulnerable rangeFixed inDependents
github.com/basekick-labs/arc—0.0.0-20260615160325-38402ad2ebdd—

Weakness Classification(3)

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

Data Freshness Timeline

(refreshed 12× in last 7d / 38× 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. 2026-09-18 19:28 UTCEPSS rescore
  2. 2026-09-18 14:20 UTCEG score recompute
  3. 2026-09-17 19:31 UTCEPSS rescore
  4. 2026-09-17 11:58 UTCEG score recompute
  5. 2026-09-16 14:08 UTCEPSS rescore
  6. 2026-09-16 09:52 UTCEG score recompute
  7. 2026-09-16 05:15 UTCEPSS rescore
  8. 2026-09-15 07:45 UTCEG score recompute
  9. 2026-09-15 03:11 UTCEPSS rescore
  10. 2026-09-14 05:38 UTCEG score recompute
  11. 2026-09-13 16:47 UTCEPSS rescore
  12. 2026-09-13 03:32 UTCEG score recompute
  13. 2026-09-12 01:25 UTCEG score recompute
  14. 2026-09-11 14:53 UTCEPSS rescore
  15. 2026-09-10 23:18 UTCEG score recompute
  16. 2026-09-10 09:35 UTCEPSS rescore
  17. 2026-09-09 00:26 UTCEG score recompute
  18. 2026-09-08 22:01 UTCEPSS rescore
  19. 2026-09-07 16:01 UTCEPSS rescore
  20. 2026-09-07 15:20 UTCEG score recompute
  21. 2026-09-06 13:47 UTCEPSS rescore
  22. 2026-09-06 13:12 UTCEG score recompute
  23. 2026-09-05 11:06 UTCEG score recompute
  24. 2026-09-04 08:54 UTCEG score recompute
  25. 2026-09-04 05:06 UTCEPSS rescore
Show 13 more
  1. 2026-09-03 06:44 UTCEG score recompute
  2. 2026-09-02 14:12 UTCEPSS rescore
  3. 2026-09-02 04:35 UTCEG score recompute
  4. 2026-09-01 13:54 UTCEPSS rescore
  5. 2026-09-01 04:40 UTCEPSS rescore
  6. 2026-09-01 02:23 UTCEG score recompute
  7. 2026-09-01 02:10 UTCEG score recompute
  8. 2026-08-31 02:49 UTCEG score recompute
  9. 2026-08-30 19:17 UTCEPSS rescore
  10. 2026-08-30 01:22 UTCEPSS rescore
  11. 2026-08-28 22:35 UTCEG score recompute▲ 6.90
  12. 2026-08-28 22:34 UTCNVD updateCVSS v3 → 6.9 · CVSS v4 → 6.9
  13. 2026-08-28 21:11 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-55678?
CVE-2026-55678 is a medium vulnerability published on August 28, 2026. Arc is an open, SQL-native time-series database for telemetry. From 26.02.1 until 26.06.2, Arc Enterprise clustering accepts cluster join requests without authentication when cluster.enabled is true but cluster.sharedsecret is not configured. The defaults in internal/config/config.go set…
When was CVE-2026-55678 disclosed?
CVE-2026-55678 was first published in the National Vulnerability Database on August 28, 2026, with the most recent update on September 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55678 actively exploited?
CVE-2026-55678 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 67.4% of all scored CVEs.
What is the CVSS score of CVE-2026-55678?
CVE-2026-55678 has a CVSS v3 base score of 6.9 (NVD).
How do I remediate CVE-2026-55678?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55678, 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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