The Model Context Protocol Python SDK is the official Python SDK for Model Context Protocol servers and clients. From 1.10.0 until 1.30.0 and 2.2.0, server-side bearer authentication configured through AuthSettings with token_verifier accepts a valid token issued for another service when the authorization server serves multiple resources and the TokenVerifier does not independently validate the aud audience. This resource-confusion flaw lets a token holder authenticate to the wrong MCP server and exercise that token's resulting access. This issue is fixed in versions 1.30.0 and 2.2.0.
CVE-2026-116684
This medium-severity CVE scores 6.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4% (30th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.
Also known asEUVD-2026-111369 (ENISA EUVD) · GHSA-w4fh-qvv9-3v23 (GitHub Security Advisories)Source: ENISA EUVD
- Lower severity and no public exploit yet
A fix is available — apply it.
- CVSS v3
- 6.8
- EG Score
- 6.8MEDIUMlow confidence
- EG Risk
- 31EG Risk 31/100
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)Severity68% × 45%Impact severity (EG Severity): CVSS 6.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation0% × 40%No KEV listing, EG-KEV tier or EPSS when EchelonGraph scored this CVE.Automatability0% × 15%CISA's BOD 26-04 default: no one has published Automatable for this CVE, and CISA treats it as “no” for a CVE not in KEV.SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from 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. - EPSS PROB
- 0.4%
- EPSS %ILE
- 30th
- 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 (6.8): severity, escalated by confirmed exploitation. This CVE's 6.8 is its impact severity (EG Severity), not escalated.
- EG Severity
- 6.8 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
- EG Likelihood
- 0.4% within 30 daysSource: FIRST EPSS. 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 or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines.
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from 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; Fix on system upgrade if it is not.
In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” 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
October 27, 2026
Last Modified
October 28, 2026
Advisory Details (7)
Auto-updated Oct 27, 2026Server bearer-token authentication accepts tokens issued for a different resource server · Advisory · modelcontextprotocol/python-sdk · GitHub
https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-w4fh-qvv9-3v23v2.2.0
Patch available: modelcontextprotocol/python-sdk v2.2.0
https://github.com/modelcontextprotocol/python-sdk/releases/tag/v2.2.0v1.30.0
Patch available: modelcontextprotocol/python-sdk v1.30.0
https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.30.0[v1.x] Add AuthSettings.validate_token_resource to check a bearer token's resource
Patch available: modelcontextprotocol/python-sdk v1.30.0 (PR #3451 merged 2026-09-05)
https://github.com/modelcontextprotocol/python-sdk/pull/3451Add AuthSettings.validate_token_resource to check a bearer token's resource
Patch available: modelcontextprotocol/python-sdk v2.2.0 (PR #3447 merged 2026-09-05)
https://github.com/modelcontextprotocol/python-sdk/pull/3447commit 8c2fa6eabacd (modelcontextprotocol/python-sdk)
Patch available: modelcontextprotocol/python-sdk v1.30.0 (contains commit 8c2fa6eabacd)
https://github.com/modelcontextprotocol/python-sdk/commit/8c2fa6eabacde869d75568e33b9d466b58c2f512commit 0c9136841ff0 (modelcontextprotocol/python-sdk)
Patch available: modelcontextprotocol/python-sdk v2.2.0 (contains commit 0c9136841ff0)
https://github.com/modelcontextprotocol/python-sdk/commit/0c9136841ff092987a20700ff9c2c9789bda2f40Vendor Advisories for CVE-2026-116684(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)
PyPI(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| mcp | 2.0.0, 2.0.1, 2.1.0, 2.1.1 |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 6× in last 7d / 6× 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.
- 2026-10-29 16:32 UTCEPSS rescoreEPSS 0.4% · 30th percentile
- 2026-10-28 16:31 UTCEPSS rescoreEPSS 0.4% · 30th percentile
- 2026-10-27 20:26 UTCEG score recompute
- 2026-10-27 20:01 UTCENISA EUVD ID recordedEUVD-2026-111369 · Source: ENISA EUVD
- 2026-10-27 19:20 UTCEG score recomputeFirst assessed: 6.8 MEDIUM
- 2026-10-27 19:19 UTCMITRE cvelistV5first tracked
Related CVEs(same product + same CWE)
Same product
9 shownPyPI:mcp
Frequently asked(5)
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Dependency Blast Radius
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