GHSA-8r9q-7v3j-jr4g — @modelcontextprotocol/sdk
Fix: modelcontextprotocol/typescript-sdk@7f0cf73GHSA-8r9q-7v3j-jr4g is a CWE-1333 vulnerability in @modelcontextprotocol/sdk. A fix is available for @modelcontextprotocol/sdk — see the affected versions and patch details below.
Anthropic's MCP TypeScript SDK has a ReDoS vulnerability
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for GHSA-8r9q-7v3j-jr4g.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
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.
@modelcontextprotocol/sdknpmDescription
Impact
A ReDoS vulnerability in the UriTemplate class allows attackers to cause denial of service. The partToRegExp() function generates a regex pattern with nested quantifiers (([^/]+(?:,[^/]+)*)) for exploded template variables (e.g., {/id*}, {?tags*}), causing catastrophic backtracking on malicious input.
Who is affected: MCP servers that register resource templates with exploded array patterns and accept requests from untrusted clients.
Attack result: An attacker sends a crafted URI via resources/read request, causing 100% CPU utilization, server hang/crash, and denial of service for all clients.
Affected Versions
All versions of @modelcontextprotocol/sdk prior to the patched release.
Patches
v1.25.2 contains b392f02ffcf37c088dbd114fedf25026ec3913d3 the fix modifies the regex pattern to prevent backtracking.
Workarounds
- Avoid using exploded patterns (
{/id*},{?tags*}) in resource templates - Implement request timeouts and rate limiting
- Validate URIs before processing to reject suspicious patterns
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @modelcontextprotocol/sdk | ≥ 1.3.0&&< 1.25.2 | 1.25.2npm install @modelcontextprotocol/sdk@1.25.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @modelcontextprotocol/sdk, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @modelcontextprotocol/sdk to 1.25.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-8r9q-7v3j-jr4g is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-8r9q-7v3j-jr4g can be triaged on real exposure rather than presence alone.
Tailored to GHSA-8r9q-7v3j-jr4g. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-8r9q-7v3j-jr4g in your dependencies?
O3 Security finds GHSA-8r9q-7v3j-jr4g across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.