CVE-2026-55678

MEDIUMPre-NVD 6.96.9
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This medium-severity CVE scores 6.9 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.7% (50th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
Elevated
6.9EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.7%CVSS: 6.9Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

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
6.9MEDIUMmedium confidence
EG Risk
62
EG Risk 62/100

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 (value × EchelonGraph’s weight)
Severity69% × 45%
The EG Score, 6.9 of 10.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.7%
EPSS %ILE
50th
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

August 28, 2026

Last Modified

September 9, 2026

Advisory Details (4)

Auto-updated Aug 28, 2026
Patch available. Sources: github, github_commit, github_pr, github_release.
GitHub advisoryMentions a patch (unverified)

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 pull request

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 rangeFix by version rangeDependents
github.com/basekick-labs/arc—
  • every version up to 0.0.0-20260615160325-38402ad2ebdd: fixed in 0.0.0-20260615160325-38402ad2ebdd
—

Weakness Classification(3)

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

Data Freshness Timeline

(refreshed 13× in last 7d / 52× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

  1. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  2. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  3. 2026-10-12 15:55 UTCEG score recompute
  4. 2026-10-11 19:38 UTCEG score recompute
  5. 2026-10-11 16:54 UTCEG score recompute
  6. 2026-10-11 14:16 UTCEG score recompute
  7. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  8. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  9. 2026-10-10 05:15 UTCEG score recompute
  10. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  11. 2026-10-09 02:36 UTCEG score recompute
  12. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  13. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  14. 2026-10-07 09:50 UTCEG score recompute
  15. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  16. 2026-10-06 07:27 UTCEG score recompute
  17. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  18. 2026-10-05 04:52 UTCEG score recompute
  19. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  20. 2026-10-04 02:44 UTCEG score recompute
  21. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  22. 2026-10-03 00:37 UTCEG score recompute
  23. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  24. 2026-10-01 22:31 UTCEG score recompute
  25. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.7% · 49th percentile
Show 56 more
  1. 2026-09-30 19:48 UTCEG score recompute
  2. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  3. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  4. 2026-09-29 14:32 UTCEG score recompute
  5. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  6. 2026-09-28 12:16 UTCEG score recompute
  7. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  8. 2026-09-27 10:09 UTCEG score recompute
  9. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  10. 2026-09-26 08:02 UTCEG score recompute
  11. 2026-09-25 03:14 UTCEG score recompute
  12. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  13. 2026-09-24 00:54 UTCEG score recompute
  14. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  15. 2026-09-22 22:48 UTCEG score recompute
  16. 2026-09-21 20:41 UTCEG score recompute
  17. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  18. 2026-09-19 16:27 UTCEG score recompute
  19. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  20. 2026-09-18 14:20 UTCEG score recompute
  21. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  22. 2026-09-17 11:58 UTCEG score recompute
  23. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  24. 2026-09-16 09:52 UTCEG score recompute
  25. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  26. 2026-09-15 07:45 UTCEG score recompute
  27. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  28. 2026-09-14 05:38 UTCEG score recompute
  29. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  30. 2026-09-13 03:32 UTCEG score recompute
  31. 2026-09-12 01:25 UTCEG score recompute
  32. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  33. 2026-09-10 23:18 UTCEG score recompute
  34. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  35. 2026-09-09 00:26 UTCEG score recompute
  36. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  37. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  38. 2026-09-07 15:20 UTCEG score recompute
  39. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  40. 2026-09-06 13:12 UTCEG score recompute
  41. 2026-09-05 11:06 UTCEG score recompute
  42. 2026-09-04 08:54 UTCEG score recompute
  43. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  44. 2026-09-03 06:44 UTCEG score recompute
  45. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  46. 2026-09-02 04:35 UTCEG score recompute
  47. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  48. 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  49. 2026-09-01 02:23 UTCEG score recompute
  50. 2026-09-01 02:10 UTCEG score recompute
  51. 2026-08-31 02:49 UTCEG score recompute
  52. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  53. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  54. 2026-08-28 22:35 UTCEG score recomputeFirst assessed: 6.9 MEDIUM
  55. 2026-08-28 22:34 UTCNVD updateCVSS v3 → 6.9 · CVSS v4 → 6.9
  56. 2026-08-28 21:11 UTCEG score recompute

Related CVEs(same product + same CWE)

Same product

2 shown

Go:github.com/basekick-labs/arc

Frequently asked(5)

What is CVE-2026-55678?
CVE-2026-55678 is a medium-severity vulnerability; its CVE record was 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 the CVE record for CVE-2026-55678 published?
The CVE record for CVE-2026-55678 was published on August 28, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of September 9, 2026; the record at its source may have been updated since.
Is CVE-2026-55678 actively exploited?
CVE-2026-55678 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.7% probability of exploitation in the next 30 days (50th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-55678?
CVE-2026-55678 has a CVSS base score of 6.9 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-55678?
A fix for CVE-2026-55678 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-55678 are linked in the Vendor Advisories panel on this page.

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