How severe is CVE-2026-62264?

CVE-2026-62264 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2026-62264?

CVE-2026-62264 affects the following packages: @sylphx/pdf-reader-mcp (npm). Ecosystems affected: npm.

How do I fix CVE-2026-62264?

Update @sylphx/pdf-reader-mcp to 3.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-62264 is resolved across your whole dependency graph.

How do I detect CVE-2026-62264 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @sylphx/pdf-reader-mcp, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-62264 if there is no patch (or I can't update yet)?

Restrict outbound requests from the affected component to an allowlist of hosts, block access to link-local and internal address ranges at the network layer, and require authentication on internal services so a forged request cannot reach them unauthenticated.

Is CVE-2026-62264 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-62264 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

When was CVE-2026-62264 published, and has it been updated?

CVE-2026-62264 was published on October 29, 2026 and was last updated on October 29, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

HIGH severity

CVE-2026-62264 — @sylphx/pdf-reader-mcp

HIGHFix: SylphxAI/anymd#332

CVE-2026-62264 is a high-severity (CVSS 7.5) vulnerability in @sylphx/pdf-reader-mcp. A fix is available for @sylphx/pdf-reader-mcp — see the affected versions and patch details below.

@sylphx/pdf-reader-mcp: HTTP transport accepts unauthenticated requests despite a configured MCP_API_KEY

Published

Oct 29, 2026

Updated

Oct 29, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 29, 2026 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

1other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

@sylphx/pdf-reader-mcpnpm

3Kdownloads / week

Description

Impact

When @sylphx/pdf-reader-mcp is run as an HTTP server (MCP_TRANSPORT=http), it reads the MCP_API_KEY environment variable and logs API key authentication enabled (X-API-Key header) at startup, but it never validated the X-API-Key header on incoming requests. The key was read into a variable and never enforced on the request path.

As a result, the /mcp endpoint accepted unauthenticated requests. Combined with the default bind address of 0.0.0.0 (all interfaces), any client able to reach the port could invoke every PDF tool and read the contents of any PDF the server process could open anywhere on the host. URL-based sources also enable limited SSRF (private/loopback addresses are blocked by default unless --allow-private-ips is set).

The misleading startup log made the exposure silent: an operator who set MCP_API_KEY reasonably believed the server was protected when it was not.

This affects only the opt-in HTTP transport; the default stdio transport is unaffected.

Patches

Fixed in @sylphx/[email protected]. The fix enforces the X-API-Key header with a constant-time comparison (rejecting missing/mismatched keys with HTTP 401), changes the default bind host to 127.0.0.1 (loopback), and emits a startup warning when binding a non-loopback host without an API key.

Workarounds

For deployments that cannot upgrade immediately:

Bind to loopback only: MCP_HTTP_HOST=127.0.0.1.
Place a reverse proxy in front that enforces authentication.
Use the default stdio transport instead of HTTP.
Restrict filesystem reach with --allow-dir / MCP_PDF_ALLOWED_DIRS.

Reported privately by novice-22 via responsible disclosure.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`@sylphx/pdf-reader-mcp`	≥ 2.2.0&&< 3.0.1	3.0.1`npm install @sylphx/pdf-reader-mcp@3.0.1`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @sylphx/pdf-reader-mcp, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @sylphx/pdf-reader-mcp to 3.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-62264 is resolved across your whole dependency graph.
Workarounds
Restrict outbound requests from the affected component to an allowlist of hosts, block access to link-local and internal address ranges at the network layer, and require authentication on internal services so a forged request cannot reach them unauthenticated.

Frequently Asked Questions

### Impact When `@sylphx/pdf-reader-mcp` is run as an HTTP server (`MCP_TRANSPORT=http`), it reads the `MCP_API_KEY` environment variable and logs `API key authentication enabled (X-API-Key header)` at startup, but it never validated the `X-API-Key` header on incoming requests. The key was read into a variable and never enforced on the request path. As a result, the `/mcp` endpoint accepted **unauthenticated** requests. Combined with the default bind address of `0.0.0.0` (all interfaces), any client able to reach the port could invoke every PDF tool and read the contents of any PDF the serve

O3 Security · Impact-Aware SCA

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