CVE-2026-48529
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedGitHub MCP Server is GitHub's official MCP Server. From 0.22.0 until 1.1.2, when running in HTTP mode with --lockdown-mode enabled, the RepoAccessCache is implemented as a process-global singleton initialized with the first authenticated user's GraphQL client. All subsequent requests from different users share this singleton and their lockdown-related GraphQL queries are executed using the first user's credentials. The singleton is never updated to reflect later users' tokens. This vulnerability is fixed in 1.1.2.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceIn GitHub MCP Server versions 0.22.0 through 1.1.2, when running in HTTP mode with --lockdown-mode enabled, the RepoAccessCache is implemented as a process-global singleton initialized with the first authenticated user's GraphQL client. All subsequent requests from different users share this singleton, causing their lockdown-related GraphQL queries to execute using the first user's credentials instead of their own.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- High
- Privileges
- Low
- User interaction
- None
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- Low
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:L
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check installed version of GitHub MCP ServerRun `github-mcp-server --version` or check via package manager (npm list -g @modelcontextprotocol/server-github)Affected if Version is between 0.22.0 and 1.1.2 inclusive
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Verify HTTP mode is enabledCheck the process command line arguments or configuration file for the presence of HTTP server flags (such as --http, --port, or similar HTTP mode indicators)Affected if Server is running with HTTP mode enabled (not stdio mode)
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Verify lockdown-mode is enabledCheck the process command line arguments or configuration file for `--lockdown-mode` flag or equivalent settingAffected if Lockdown mode is enabled via --lockdown-mode flag or config setting
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Check for multiple authenticated usersReview server logs or authentication records to confirm multiple different users have authenticated to the serverAffected if Multiple authenticated users have accessed the server; the first user's credentials would be reused for subsequent users
You are affected if running GitHub MCP Server version 0.22.0 through 1.1.2 in HTTP mode with lockdown-mode enabled, and multiple users have authenticated (the second user onward would inherit the first user's permissions).
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scopedUpgrade to GitHub MCP Server version 1.1.2 or later, which fixes the singleton caching issue so each user's credentials are properly used for their requests.
1.1.2
- Identify all instances of GitHub MCP Server running versions 0.22.0 through 1.1.1 in your environment
- Stop the affected GitHub MCP Server instances
- Upgrade GitHub MCP Server to version 1.1.2 or later
- Restart the service
- Verify that --lockdown-mode is functioning correctly with the upgrade by testing that different users' GraphQL queries use their own credentials
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation3.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,272.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-48529 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-48529 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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