CVE-2026-104850

HIGHPre-NVD 7.57.5
EchelonGraph scoreLOW confidence

This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). 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: secondary
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: —CVSS: 7.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

MCP TypeScript SDK is the official TypeScript SDK for Model Context Protocol servers and clients. Starting in version 1.12.0 and prior to versions 1.31.0 and 2.2.0, the SDK's OAuth client support let the MCP server a client connected to decide which authorization server received the client's OAuth credentials. Stored and pre-provisioned credentials were not bound to the authorization server they belong to. A malicious or compromised MCP server could name its own authorization server in its protected resource metadata. Without any user interaction, the client would send that server the refresh_token and client_secret stored from an earlier sign-in (1.x), or the configured client_secret or signed assertion of a bundled non-interactive provider (1.x and 2.x). Only those applications that use the SDK as an MCP client over HTTP with an authProvider: your own OAuthClientProvider, or the bundled ClientCredentialsProvider, PrivateKeyJwtProvider, StaticPrivateKeyJwtProvider or (2.x) CrossAppAccessProvider and that may connect to an MCP server the owners does not fully trust while holding credentials for a legitimate authorization server are affected. @modelcontextprotocol/sdk 1.31.0 (1.x) and @modelcontextprotocol/client 2.2.0 (2.x) patch the issue. A workaround for those who cannot upgrade is available. 2.0.0 and 2.1.0 already accept expectedIssuer. On 1.x, the only workaround is to connect OAuth-enabled clients only to MCP servers you trust.

CVSS v3
7.5
EG Score
7.5HIGHlow confidence
EG Risk
38
EG Risk 38/100CISA SSVC

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
Severity75% × 45%
Exploitation0% × 40%
Automatability30% × 15%
CISA SSVC: Track at low or medium mission impact; Track or Attend at high (mission-essential systems).
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
—
EPSS %ILE
—
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track or Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact partial (CVSS below 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

October 6, 2026

Last Modified

October 6, 2026

Advisory Details (4)

Auto-updated Oct 6, 2026
Patch available. Sources: github, github_pr, github_commit, github_release.
github_release Patch Available

2.2.0

Patch available: modelcontextprotocol/typescript-sdk v2.2.0

https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/v2.2.0
github_commit Patch Available

commit edd12e282620 (modelcontextprotocol/typescript-sdk)

Patch available: modelcontextprotocol/typescript-sdk @modelcontextprotocol/[email protected] (contains commit edd12e282620)

https://github.com/modelcontextprotocol/typescript-sdk/commit/edd12e282620ebf770d67316f19cf91d4112a1bd
github_pr Patch Available

fix(client): deprecate omitting expectedIssuer and apply the SEP-2352 issuer check consistently

Patch available: modelcontextprotocol/typescript-sdk @modelcontextprotocol/[email protected] (PR #2887 merged 2026-09-28)

https://github.com/modelcontextprotocol/typescript-sdk/pull/2887
githubMentions a patch (unverified)

OAuth client could send credentials to an authorization server chosen by the MCP server · Advisory · modelcontextprotocol/typescript-sdk · GitHub

https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-6qxp-vccf-f47h

Vendor Advisories for CVE-2026-104850(1)

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

Affected Packages

(2 across 1 ecosystem)
npm(2)
PackageVulnerable rangeFix by version rangeDependents
@modelcontextprotocol/client—
  • 2.0.0 up to 2.2.0: fixed in 2.2.0
—
@modelcontextprotocol/sdk—
  • 1.12.0 up to 1.31.0: fixed in 1.31.0
—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 2× in last 7d / 2× 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. 2026-10-06 17:19 UTCEG score recompute
  2. 2026-10-06 15:59 UTCEG score recompute

Related CVEs(same product + same CWE)

Same product

3 shown

npm:@modelcontextprotocol/sdk

Frequently asked(4)

What is CVE-2026-104850?
CVE-2026-104850 is a high vulnerability published on October 6, 2026. MCP TypeScript SDK is the official TypeScript SDK for Model Context Protocol servers and clients. Starting in version 1.12.0 and prior to versions 1.31.0 and 2.2.0, the SDK's OAuth client support let the MCP server a client connected to decide which authorization server received the client's OAuth…
When was CVE-2026-104850 disclosed?
CVE-2026-104850 was first published on October 6, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
What is the CVSS score of CVE-2026-104850?
CVE-2026-104850 has a CVSS base score of 7.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
How do I remediate CVE-2026-104850?
A fix for CVE-2026-104850 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-104850 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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