CVE-2026-91988

HIGHPre-NVD 8.18.1—
EchelonGraph scoreHIGH confidence

Score 8.1 from GitHub Security Advisory (severity: CRITICAL) published 2026-09-15. a secondary CVSS source baseline 8.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
8.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.1Exploit: None knownExposed: 0

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

atomic-agents-stack before 1.1.0 accepts cleartext HTTP schemes in the HTTP MCP server-registry backend factory, allowing network man-in-the-middle attackers to rewrite catalog responses. Attackers can inject arbitrary command and argument values that are spawned as local subprocesses by MCPClientPool to achieve code execution on the agent host.

CVSS v3
8.1
EG Score
8.1(high)
EG Risk
37(Track)
EG Risk 37/100SSVC: 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
Severity81% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
17%
KEV
Not listed

Published

September 15, 2026

Last Modified

September 15, 2026

Advisory Details (2)

Auto-updated Sep 15, 2026
Patch available. Sources: github.
generic

atomic-agents-stack before 1.1.0 Remote Code Execution via HTTP MCP | Advisories | VulnCheck

https://www.vulncheck.com/advisories/atomic-agents-stack-before-1.1.0-remote-code-execution-via-http-mcp
github Patch Available

HTTP MCP catalog accepts cleartext http and spawns catalog-supplied commands (MITM to RCE) · Advisory · dep0we/atomic-agents-stack · GitHub

https://github.com/dep0we/atomic-agents-stack/security/advisories/GHSA-xhcr-cqfr-m3hv

Vendor Advisories for CVE-2026-91988(1)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 22× in last 7d / 22× 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 11:50 UTCGHSA enrichment
  2. 2026-09-20 00:10 UTCEG score recompute
  3. 2026-09-20 00:10 UTCGHSA enrichment
  4. 2026-09-19 12:40 UTCGHSA enrichment
  5. 2026-09-19 01:07 UTCEG score recompute
  6. 2026-09-19 01:07 UTCGHSA enrichment
  7. 2026-09-18 19:28 UTCEPSS rescore
  8. 2026-09-18 13:37 UTCGHSA enrichment
  9. 2026-09-18 02:07 UTCEG score recompute
  10. 2026-09-18 02:07 UTCGHSA enrichment
  11. 2026-09-17 19:32 UTCEPSS rescore
  12. 2026-09-17 14:36 UTCGHSA enrichment
  13. 2026-09-17 03:05 UTCGHSA enrichment
  14. 2026-09-16 15:34 UTCEG score recompute
  15. 2026-09-16 15:34 UTCGHSA enrichment
  16. 2026-09-16 14:09 UTCEPSS rescore
  17. 2026-09-16 04:03 UTCEG score recompute
  18. 2026-09-16 04:03 UTCGHSA enrichment
  19. 2026-09-15 16:32 UTCEG score recompute
  20. 2026-09-15 15:59 UTCEG score recompute
  21. 2026-09-15 15:23 UTCEG score recompute
  22. 2026-09-15 15:22 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-91988?
CVE-2026-91988 is a high vulnerability published on September 15, 2026. atomic-agents-stack before 1.1.0 accepts cleartext HTTP schemes in the HTTP MCP server-registry backend factory, allowing network man-in-the-middle attackers to rewrite catalog responses. Attackers can inject arbitrary command and argument values that are spawned as local subprocesses by…
When was CVE-2026-91988 disclosed?
CVE-2026-91988 was first published in the National Vulnerability Database on September 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-91988 actively exploited?
CVE-2026-91988 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 83.3% of all scored CVEs.
What is the CVSS score of CVE-2026-91988?
CVE-2026-91988 has a CVSS v3 base score of 8.1 (NVD).
How do I remediate CVE-2026-91988?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-91988, 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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