mcp-memory-service: OAuth read-only clients can write and delete memories through MCP tools/call

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

8.1 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

EPSS

• CVE-2026-49291: 0.49% estimated exploitation activity in the next 30 days; percentile 42.06 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The HTTP MCP JSON-RPC endpoint at /mcp requires only OAuth read scope for all requests, then dispatches tools/call directly to handlers that include mutating tools. A read-only OAuth client can call storememory and deletememory through MCP even though the corresponding REST endpoints require write scope. Technical Details src/mcpmemoryservice/web/api/mcp.py declares mcpendpoint with user: AuthenticationResult = Depends(requirereadaccess). For tools/call, it extracts the requested tool name and arguments, then calls handletoolcall(storage, toolname, arguments) without passing the authenticated user or checking a per-tool required scope. The MCP tool registry includes both read tools and write tools. In the same handler file, storememory creates a Memory object and calls storage.store(...), while deletememory calls storage.delete(contenthash). These operations are reachable with only the read scope. The REST endpoint demonstrates the intended boundary: POST /api/memories uses…

Published by the source

26 Jun 2026, 21:04 UTC

Last modified by the source

13 Jul 2026, 16:42 UTC

Source last checked

26 Oct 2026, 13:46 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-2r68-g678-7qr3

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-2r68-g678-7qr3

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# Patch Next advisory brief: CVE-2026-49291

Advisory: mcp-memory-service: OAuth read-only clients can write and delete memories through MCP tools/call
IDs: CVE-2026-49291, GHSA-2r68-g678-7qr3
Record: https://patchnext.com/advisories/cve-2026-49291 (revision 2, source checked 26 Oct 2026, 13:46 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: mcp-memory-service 10.65.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI mcp-memory-service: affected <= 10.65.1; fixed in 10.65.3

## Suggested inspection (read-only)
- `python -m pip show mcp-memory-service`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on mcp-memory-service.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-2r68-g678-7qr3 (OSV record GHSA-2r68-g678-7qr3 lists affected ranges: PyPI mcp-memory-service >=0 <10.65.3 (fixed))
- Verified: https://github.com/advisories/GHSA-2r68-g678-7qr3 (GitHub-reviewed advisory GHSA-2r68-g678-7qr3 lists affected ranges: PyPI mcp-memory-service >=0 <=10.65.1)

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