CVE-2026-32871

CRITICALNVD 10.010.0
EchelonGraph scoreMEDIUM confidence

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

Score 10.0 from GitHub Security Advisory (severity: CRITICAL) published 2026-03-31. NVD baseline CVSS 10.0; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Trending — 4 sources updated this weekElevated

Also known asEUVD-2026-18250 (ENISA EUVD) · GHSA-vv7q-7jx5-f767 (GitHub Security Advisories)Source: ENISA EUVD

10.0EG
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: 0.9%CVSS: 10.0Exploit: No code on recordExposed services: Not assessed

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
10.0CRITICALmedium confidence
EG Risk
76
EG Risk 76/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity100% × 45%
Impact severity (EG Severity): CVSS 10.0 of 10. Never the KEV-floored or EPSS-lifted EG Score.
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, Track* at medium and Attend at high mission impact.
Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (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
0.9%
EPSS %ILE
60th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (10.0): severity, escalated by confirmed exploitation. This CVE's 10.0 is its impact severity (EG Severity), not escalated.

EG Severity
10.0 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.9% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-31). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track* at medium mission impactTrack at low, Track* at medium and Attend at high mission impact.CISA BOD 26-04: 3 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low, Track* at medium and Attend at high mission impact.

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 total (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)3 days if the affected system is publicly exposed; 60 days if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact total (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

April 2, 2026

Last Modified

October 26, 2026

Advisory Details (8)

Auto-updated Oct 26, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_pr, github_release, github, redhat.
GitHub advisoryMentions a patch (unverified)🟡 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
Red Hat

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
Red HatMentions a patch (unverified)

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
Red HatMentions a patch (unverified)
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 pull request Patch Available

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

Patch available: PrefectHQ/fastmcp v4.0.0a2 (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 v4.0.0a2 (contains commit 40bdfb6b1de0)

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

Vendor Advisories for CVE-2026-32871(2)

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

Patch Availability(2)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatsatellite/foreman-mcp-server-rhel9:17827393442026-07-07redhat
pipfastmcp @ 3.2.0 (fixes < 3.2.0)—ghsa

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 rangeFix by version rangeDependents
fastmcp0.1.0 ... 3.1.1 (91 versions)
  • every version up to 3.2.0: fixed in 3.2.0
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 22× in last 7d / 78× 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.

Showing the most recent 98 of 301 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 2 repeat rows among the latest 100 are merged into the row they repeat. The 203 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.9% · 60th percentile
  2. 2026-11-01 15:09 UTCVendor advisory
  3. 2026-11-01 15:09 UTCGHSA enrichmentGHSA-vv7q-7jx5-f767 · GitHub severity CRITICAL · GitHub CVSS 10.0
  4. 2026-11-01 07:54 UTCGHSA enrichmentGHSA-vv7q-7jx5-f767 · GitHub severity CRITICAL · GitHub CVSS 10.0
  5. 2026-11-01 07:54 UTCEG score recompute
  6. 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.9% · 60th percentile
  7. 2026-10-31 14:43 UTCEG score recompute
  8. 2026-10-31 14:43 UTCVendor advisory
  9. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.9% · 60th percentile
  10. 2026-10-30 14:17 UTCEG score recompute
  11. 2026-10-30 14:17 UTCVendor advisory
  12. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  13. 2026-10-29 13:51 UTCEG score recompute
  14. 2026-10-29 13:51 UTCVendor advisory
  15. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  16. 2026-10-28 13:23 UTCEG score recompute
  17. 2026-10-28 13:23 UTCVendor advisory
  18. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  19. 2026-10-27 12:50 UTCVendor advisory
  20. 2026-10-26 21:28 UTCEG score recompute
  21. 2026-10-26 21:28 UTCVendor advisory
  22. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  23. 2026-10-26 15:28 UTCEG score recompute
  24. 2026-10-26 15:28 UTCVendor advisory
  25. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.9% · 59th percentile
Show 73 more
  1. 2026-10-25 14:25 UTCEG score recompute
  2. 2026-10-25 14:25 UTCVendor advisory
  3. 2026-10-24 16:32 UTCEPSS rescoreEPSS 1.4% · 71st percentile
  4. 2026-10-24 13:58 UTCEG score recompute
  5. 2026-10-24 13:58 UTCVendor advisory
  6. 2026-10-23 16:31 UTCEPSS rescoreEPSS 1.4% · 71st percentile
  7. 2026-10-23 13:32 UTCEG score recompute
  8. 2026-10-23 13:32 UTCVendor advisory
  9. 2026-10-22 16:34 UTCEPSS rescoreEPSS 1.4% · 71st percentile
  10. 2026-10-22 13:06 UTCEG score recompute
  11. 2026-10-22 13:06 UTCVendor advisory
  12. 2026-10-21 16:32 UTCEPSS rescoreEPSS 1.4% · 71st percentile
  13. 2026-10-21 12:38 UTCEG score recompute
  14. 2026-10-21 12:38 UTCVendor advisory
  15. 2026-10-20 16:33 UTCEPSS rescoreEPSS 1.4% · 71st percentile
  16. 2026-10-20 12:11 UTCEG score recompute
  17. 2026-10-20 12:11 UTCVendor advisory
  18. 2026-10-19 16:31 UTCEPSS rescoreEPSS 1.4% · 71st percentile
  19. 2026-10-19 11:43 UTCEG score recompute
  20. 2026-10-19 11:43 UTCVendor advisory
  21. 2026-10-18 16:31 UTCEPSS rescoreEPSS 1.4% · 71st percentile
  22. 2026-10-18 09:39 UTCVendor advisory
  23. 2026-10-18 03:47 UTCEG score recompute
  24. 2026-10-17 16:34 UTCEPSS rescoreEPSS 1.4% · 71st percentile
  25. 2026-10-17 08:11 UTCEG score recompute
  26. 2026-10-17 08:11 UTCVendor advisory
  27. 2026-10-16 16:41 UTCEPSS rescoreEPSS 1.4% · 71st percentile
  28. 2026-10-16 07:44 UTCEG score recompute
  29. 2026-10-16 07:44 UTCVendor advisory
  30. 2026-10-15 16:32 UTCEPSS rescoreEPSS 1.4% · 71st percentile
  31. 2026-10-15 06:41 UTCEG score recompute
  32. 2026-10-15 06:41 UTCVendor advisory
  33. 2026-10-14 16:32 UTCEPSS rescoreEPSS 1.4% · 71st percentile
  34. 2026-10-14 02:21 UTCEG score recompute
  35. 2026-10-14 02:21 UTCVendor advisory
  36. 2026-10-13 16:34 UTCEPSS rescoreEPSS 1.4% · 71st percentile
  37. 2026-10-12 22:38 UTCEG score recompute
  38. 2026-10-12 22:38 UTCVendor advisory
  39. 2026-10-12 16:34 UTCEPSS rescoreEPSS 1.4% · 71st percentile
  40. 2026-10-12 16:13 UTCEG score recompute
  41. 2026-10-12 08:30 UTCVendor advisory
  42. 2026-10-11 19:56 UTCEG score recompute
  43. 2026-10-11 17:09 UTCEG score recompute
  44. 2026-10-11 14:36 UTCEG score recompute
  45. 2026-10-11 13:48 UTCEPSS rescoreEPSS 1.4% · 71st percentile
  46. 2026-10-11 02:31 UTCOSV refresh
  47. 2026-10-10 20:00 UTCEPSS rescoreEPSS 1.4% · 71st percentile
  48. 2026-10-09 20:07 UTCEPSS rescoreEPSS 1.4% · 71st percentile
  49. 2026-10-08 17:12 UTCEPSS rescoreEPSS 1.4% · 71st percentile
  50. 2026-10-07 23:47 UTCEPSS rescoreEPSS 1.4% · 71st percentile
  51. 2026-10-06 15:17 UTCEPSS rescoreEPSS 1.4% · 70th percentile
  52. 2026-10-05 17:42 UTCEPSS rescoreEPSS 1.4% · 70th percentile
  53. 2026-10-04 23:22 UTCEPSS rescoreEPSS 1.4% · 70th percentile
  54. 2026-10-03 14:25 UTCEPSS rescoreEPSS 1.4% · 70th percentile
  55. 2026-10-01 19:49 UTCEPSS rescoreEPSS 1.4% · 70th percentile
  56. 2026-09-30 15:03 UTCEPSS rescoreEPSS 1.4% · 70th percentile
  57. 2026-09-28 13:51 UTCEPSS rescoreEPSS 1.4% · 70th percentile
  58. 2026-09-27 13:48 UTCEPSS rescoreEPSS 1.4% · 70th percentile
  59. 2026-09-26 15:58 UTCEPSS rescoreEPSS 1.4% · 70th percentile
  60. 2026-09-26 00:26 UTCEPSS rescoreEPSS 1.4% · 70th percentile
  61. 2026-09-21 14:19 UTCOSV refresh
  62. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  63. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  64. 2026-09-17 19:30 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  65. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  66. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  67. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  68. 2026-09-12 15:01 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  69. 2026-09-11 14:52 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  70. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  71. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  72. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  73. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.9% · 57th percentile

Frequently asked(5)

What is CVE-2026-32871?
CVE-2026-32871 is a critical-severity vulnerability; its CVE record was 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 the CVE record for CVE-2026-32871 published?
The CVE record for CVE-2026-32871 was published on April 2, 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 October 26, 2026; the record at its source may have been updated since.
Is CVE-2026-32871 actively exploited?
CVE-2026-32871 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.9% probability of exploitation in the next 30 days (60th percentile of EPSS-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?
A fix for CVE-2026-32871 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-32871 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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