CVE-2026-32871

CRITICALNVD 10.010.0—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 10.0 under NVD CVSS v3. EPSS exploit probability: 0.9%, top 43% 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, nvd
Elevated
10.0EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 10.0Exploit: Elevated riskExposed: 0

A fix is available — apply it.

FastMCP is a Pythonic way to build MCP servers and clients. Prior to version 3.2.0, the OpenAPIProvider in FastMCP exposes internal APIs to MCP clients by parsing OpenAPI specifications. The RequestDirector class is responsible for constructing HTTP requests to the backend service. A vulnerability exists in the _build_url() method. When an OpenAPI operation defines path parameters (e.g., /api/v1/users/{user_id}), the system directly substitutes parameter values into the URL template string without URL-encoding. Subsequently, urllib.parse.urljoin() resolves the final URL. Since urljoin() interprets ../ sequences as directory traversal, an attacker controlling a path parameter can perform path traversal attacks to escape the intended API prefix and access arbitrary backend endpoints. This results in authenticated SSRF, as requests are sent with the authorization headers configured in the MCP provider. This issue has been patched in version 3.2.0.

CVSS v3
10.0
EG Score
10.0(medium)
EG Risk
76(Attend)
EG Risk 76/100SSVC: 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
Severity100% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
1%
EPSS %ILE
58%
KEV
Not listed

Published

April 2, 2026

Last Modified

July 15, 2026

Advisory Details (8)

Auto-updated Sep 16, 2026
🔬 Proof of concept available. Patch available. Sources: github_release, github, redhat, github_commit, github_pr.
redhat Patch Available
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-32871.json
github Patch Available🟡 PoC Available

SSRF & Path Traversal Vulnerability in FastMCP OpenAPI Provider · Advisory · PrefectHQ/fastmcp · GitHub

https://github.com/PrefectHQ/fastmcp/security/advisories/GHSA-vv7q-7jx5-f767
redhat

2454434 – (CVE-2026-32871) CVE-2026-32871 fastmcp: FastMCP: Authenticated Server-Side Request Forgery via path traversal in OpenAPI path parameters

https://bugzilla.redhat.com/show_bug.cgi?id=2454434
redhat Patch Available

CVE-2026-32871 - Red Hat Customer Portal

Affected: Red Hat Enterprise Linux 8 or OpenShift Container Platform 4, is affected by this vulnerability and a fix may be released to a

https://access.redhat.com/security/cve/CVE-2026-32871
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:36350
github_release Patch Available

v3.2.0: Show Don't Tool

Patch available: PrefectHQ/fastmcp v3.2.0

https://github.com/PrefectHQ/fastmcp/releases/tag/v3.2.0
github_pr Patch Available

fix: URL-encode path params to prevent SSRF/path traversal (GHSA-vv7q-7jx5-f767)

Patch available: PrefectHQ/fastmcp v3.2.1 (PR #3507 merged 2026-03-15)

https://github.com/PrefectHQ/fastmcp/pull/3507
github_commit Patch Available

commit 40bdfb6b1de0 (PrefectHQ/fastmcp)

Patch available: PrefectHQ/fastmcp v3.2.1 (contains commit 40bdfb6b1de0)

https://github.com/PrefectHQ/fastmcp/commit/40bdfb6b1de0ce30609ee9ba5bb95ecd04a9fb71

Vendor Advisories for CVE-2026-32871(1)

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

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatsatellite/foreman-mcp-server-rhel9:17827393442026-07-07redhat

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.

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFixed inDependents
fastmcp0.1.0 ... 3.1.1 (91 versions)3.2.0—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 30× 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.

Showing the most recent 100 of 216 total refreshes for this CVE.

  1. 2026-09-18 19:28 UTCEPSS rescore
  2. 2026-09-18 19:28 UTCEPSS rescore
  3. 2026-09-17 19:30 UTCEPSS rescore
  4. 2026-09-16 14:08 UTCEPSS rescore
  5. 2026-09-16 05:15 UTCEPSS rescore
  6. 2026-09-13 16:47 UTCEPSS rescore
  7. 2026-09-12 15:01 UTCEPSS rescore
  8. 2026-09-11 14:52 UTCEPSS rescore
  9. 2026-09-10 09:34 UTCEPSS rescore
  10. 2026-09-08 22:00 UTCEPSS rescore
  11. 2026-09-07 16:01 UTCEPSS rescore
  12. 2026-09-06 13:47 UTCEPSS rescore
  13. 2026-09-06 13:47 UTCEPSS rescore
  14. 2026-09-04 05:06 UTCEPSS rescore
  15. 2026-09-02 14:11 UTCEPSS rescore
  16. 2026-09-02 11:34 UTCOSV refresh
  17. 2026-09-01 13:53 UTCEPSS rescore
  18. 2026-09-01 04:39 UTCEPSS rescore
  19. 2026-09-01 04:39 UTCEPSS rescore
  20. 2026-08-30 19:17 UTCEPSS rescore
  21. 2026-08-30 01:22 UTCEPSS rescore
  22. 2026-08-28 21:41 UTCEPSS rescore
  23. 2026-08-27 14:25 UTCEPSS rescore
  24. 2026-08-26 14:46 UTCEPSS rescore
  25. 2026-08-25 13:49 UTCEPSS rescore
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  1. 2026-08-24 14:17 UTCEPSS rescore
  2. 2026-08-23 00:19 UTCEPSS rescore
  3. 2026-08-21 23:49 UTCEPSS rescore
  4. 2026-08-20 22:55 UTCEPSS rescore
  5. 2026-08-20 22:55 UTCEPSS rescore
  6. 2026-08-19 17:03 UTCEPSS rescore
  7. 2026-08-18 13:48 UTCEPSS rescore
  8. 2026-08-17 13:47 UTCEPSS rescore
  9. 2026-08-16 14:56 UTCEPSS rescore
  10. 2026-08-16 09:25 UTCEG score recompute
  11. 2026-08-16 09:25 UTCVendor advisory
  12. 2026-08-16 02:14 UTCEPSS rescore
  13. 2026-08-15 01:30 UTCEPSS rescore
  14. 2026-08-14 23:23 UTCVendor advisory
  15. 2026-08-14 19:00 UTCVendor advisory
  16. 2026-08-14 14:36 UTCVendor advisory
  17. 2026-08-14 10:13 UTCVendor advisory
  18. 2026-08-14 05:50 UTCEG score recompute
  19. 2026-08-14 05:50 UTCVendor advisory
  20. 2026-08-13 22:00 UTCEPSS rescore
  21. 2026-08-13 09:59 UTCVendor advisory
  22. 2026-08-13 04:55 UTCVendor advisory
  23. 2026-08-13 00:31 UTCVendor advisory
  24. 2026-08-12 20:08 UTCEG score recompute
  25. 2026-08-12 20:08 UTCVendor advisory
  26. 2026-08-12 13:50 UTCEPSS rescore
  27. 2026-08-12 00:52 UTCVendor advisory
  28. 2026-08-11 20:29 UTCEG score recompute
  29. 2026-08-11 20:29 UTCVendor advisory
  30. 2026-08-11 07:52 UTCVendor advisory
  31. 2026-08-11 03:30 UTCEG score recompute
  32. 2026-08-11 03:30 UTCVendor advisory
  33. 2026-08-11 00:00 UTCEPSS rescore
  34. 2026-08-10 11:58 UTCVendor advisory
  35. 2026-08-10 06:32 UTCVendor advisory
  36. 2026-08-10 02:09 UTCVendor advisory
  37. 2026-08-09 21:45 UTCVendor advisory
  38. 2026-08-09 17:23 UTCEG score recompute
  39. 2026-08-09 17:23 UTCVendor advisory
  40. 2026-08-09 13:46 UTCEPSS rescore
  41. 2026-08-09 13:00 UTCVendor advisory
  42. 2026-08-09 05:22 UTCEG score recompute
  43. 2026-08-09 05:22 UTCVendor advisory
  44. 2026-08-08 16:37 UTCEPSS rescore
  45. 2026-08-08 09:01 UTCVendor advisory
  46. 2026-08-08 04:38 UTCVendor advisory
  47. 2026-08-08 00:15 UTCVendor advisory
  48. 2026-08-07 19:52 UTCEG score recompute
  49. 2026-08-07 19:52 UTCVendor advisory
  50. 2026-08-07 15:30 UTCVendor advisory
  51. 2026-08-06 17:57 UTCEG score recompute
  52. 2026-08-06 17:57 UTCVendor advisory
  53. 2026-08-06 13:46 UTCEPSS rescore
  54. 2026-08-06 09:11 UTCVendor advisory
  55. 2026-08-06 04:48 UTCVendor advisory
  56. 2026-08-06 00:25 UTCEG score recompute
  57. 2026-08-06 00:25 UTCVendor advisory
  58. 2026-08-05 19:17 UTCEPSS rescore
  59. 2026-08-04 15:10 UTCEPSS rescore
  60. 2026-08-04 10:38 UTCEPSS rescore
  61. 2026-08-04 03:52 UTCVendor advisory
  62. 2026-08-03 22:45 UTCEG score recompute
  63. 2026-08-03 22:45 UTCVendor advisory
  64. 2026-08-03 10:36 UTCEPSS rescore
  65. 2026-08-02 23:28 UTCVendor advisory
  66. 2026-08-02 19:05 UTCVendor advisory
  67. 2026-08-02 14:42 UTCEG score recompute
  68. 2026-08-02 14:42 UTCVendor advisory
  69. 2026-08-02 02:27 UTCEPSS rescore
  70. 2026-08-01 04:16 UTCEPSS rescore
  71. 2026-07-30 16:28 UTCEPSS rescore
  72. 2026-07-30 01:30 UTCEPSS rescore
  73. 2026-07-27 14:13 UTCEPSS rescore
  74. 2026-07-26 14:54 UTCEPSS rescore
  75. 2026-07-26 14:54 UTCEPSS rescore

Frequently asked(5)

What is CVE-2026-32871?
CVE-2026-32871 is a critical vulnerability published on April 2, 2026. FastMCP is a Pythonic way to build MCP servers and clients. Prior to version 3.2.0, the OpenAPIProvider in FastMCP exposes internal APIs to MCP clients by parsing OpenAPI specifications. The RequestDirector class is responsible for constructing HTTP requests to the backend service. A vulnerability…
When was CVE-2026-32871 disclosed?
CVE-2026-32871 was first published in the National Vulnerability Database on April 2, 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-2026-32871 actively exploited?
CVE-2026-32871 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 41.6% of all scored CVEs.
What is the CVSS score of CVE-2026-32871?
CVE-2026-32871 has a CVSS v3 base score of 10.0 (NVD).
How do I remediate CVE-2026-32871?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-32871, 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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