CVE-2026-90898

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-09-14. a secondary CVSS source baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.8Exploit: None knownExposed: 0

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

Bifrost registers MCP clients through its management API. A stdio client is a command plus args. Bifrost starts that program in the gateway the moment the client is added. No MCP handshake required.

The default is governance.auth_config.is_enabled=false. Auth off means every caller is a local admin. One unauthenticated POST /api/mcp/client is enough to run a program as the Bifrost process user (appuser on the official image).

 transports/v2.1.0 refuses an unauthenticated stdio registration with 403. transports/v2.0.0 still allows it.

CVSS v3
9.8
EG Score
9.8(high)
EG Risk
59(Track)
EG Risk 59/100SSVC: 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
Severity98% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
28%
KEV
Not listed

Published

September 14, 2026

Last Modified

September 18, 2026

Advisory Details (3)

Auto-updated Sep 18, 2026
Patch available. Sources: github_commit, github_pr.
github_pr Patch Available

mcp auth with ssrf checks

Patch available: maximhq/bifrost plugins/compat/v0.3.0 (PR #6757 merged 2026-09-02)

https://github.com/maximhq/bifrost/pull/6757
github_commit Patch Available

commit 12e170352bd2 (maximhq/bifrost)

Patch available: maximhq/bifrost plugins/compat/v0.3.0 (contains commit 12e170352bd2)

https://github.com/maximhq/bifrost/commit/12e170352bd25eab1ae9ba16611f1797d1fd8fdc
generic

GitHub - maximhq/bifrost: Fastest enterprise AI gateway (50x faster than LiteLLM) with adaptive load balancer, cluster mode, guardrails, 1000+ models support & <100 µs overhead at 5k RPS. · GitHub

https://github.com/maximhq/bifrost

Vendor Advisories for CVE-2026-90898(1)

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

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 45× 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. 2026-09-20 02:13 UTCGHSA enrichment
  2. 2026-09-19 21:50 UTCGHSA enrichment
  3. 2026-09-19 17:27 UTCEG score recompute
  4. 2026-09-19 17:27 UTCGHSA enrichment
  5. 2026-09-19 13:04 UTCGHSA enrichment
  6. 2026-09-19 08:42 UTCGHSA enrichment
  7. 2026-09-19 04:19 UTCGHSA enrichment
  8. 2026-09-18 23:55 UTCGHSA enrichment
  9. 2026-09-18 19:33 UTCEG score recompute
  10. 2026-09-18 19:33 UTCGHSA enrichment
  11. 2026-09-18 19:28 UTCEPSS rescore
  12. 2026-09-18 18:19 UTCGHSA enrichment
  13. 2026-09-18 13:56 UTCGHSA enrichment
  14. 2026-09-18 09:27 UTCGHSA enrichment
  15. 2026-09-18 05:04 UTCGHSA enrichment
  16. 2026-09-18 00:41 UTCGHSA enrichment
  17. 2026-09-17 20:18 UTCEG score recompute
  18. 2026-09-17 20:18 UTCGHSA enrichment
  19. 2026-09-17 19:32 UTCEPSS rescore
  20. 2026-09-17 15:55 UTCGHSA enrichment
  21. 2026-09-17 11:32 UTCGHSA enrichment
  22. 2026-09-17 07:09 UTCGHSA enrichment
  23. 2026-09-17 02:46 UTCGHSA enrichment
  24. 2026-09-16 22:21 UTCGHSA enrichment
  25. 2026-09-16 17:57 UTCEG score recompute
Show 20 more
  1. 2026-09-16 17:57 UTCGHSA enrichment
  2. 2026-09-16 14:09 UTCEPSS rescore
  3. 2026-09-16 13:14 UTCGHSA enrichment
  4. 2026-09-16 08:49 UTCEG score recompute
  5. 2026-09-16 08:49 UTCGHSA enrichment
  6. 2026-09-16 05:15 UTCEPSS rescore
  7. 2026-09-16 03:55 UTCGHSA enrichment
  8. 2026-09-15 23:30 UTCGHSA enrichment
  9. 2026-09-15 19:07 UTCGHSA enrichment
  10. 2026-09-15 14:44 UTCGHSA enrichment
  11. 2026-09-15 10:21 UTCGHSA enrichment
  12. 2026-09-15 05:58 UTCGHSA enrichment
  13. 2026-09-15 01:35 UTCGHSA enrichment
  14. 2026-09-14 21:12 UTCGHSA enrichment
  15. 2026-09-14 16:49 UTCEG score recompute
  16. 2026-09-14 16:49 UTCGHSA enrichment
  17. 2026-09-14 12:26 UTCEG score recompute
  18. 2026-09-14 11:21 UTCEG score recompute
  19. 2026-09-14 10:30 UTCEG score recompute
  20. 2026-09-14 10:29 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-90898?
CVE-2026-90898 is a critical vulnerability published on September 14, 2026. Bifrost registers MCP clients through its management API. A stdio client is a command plus args. Bifrost starts that program in the gateway the moment the client is added. No MCP handshake required. The default is governance.authconfig.isenabled=false. Auth off means every caller is a local admin.…
When was CVE-2026-90898 disclosed?
CVE-2026-90898 was first published in the National Vulnerability Database on September 14, 2026, with the most recent update on September 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-90898 actively exploited?
CVE-2026-90898 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 72.1% of all scored CVEs.
What is the CVSS score of CVE-2026-90898?
CVE-2026-90898 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-90898?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-90898, 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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