Model Context Protocol TypeScript SDK: One HTTP request within the default size limit could exhaust server memory during validation
Affects @modelcontextprotocol/sdk 1.3.0 through 1.31.0 and @modelcontextprotocol/server 2.0.0 through 2.2.0 where the HTTP transport is reachable by clients not fully trusted. Fixed in SDK 1.32.0 and server 2.3.0.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in typescript-sdk 1.32.0 · server 2.3.0 · sdk 1.32.0
- Who is exposed
- Default setups
Do first: Check every install: default setups are affected.
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 30/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Default setups
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
The Model Context Protocol TypeScript SDK's HTTP servers (@modelcontextprotocol/sdk and @modelcontextprotocol/server) can be affected by a single request, sent remotely without logging in, that stays within the default 4 MiB size limit but contains enough array elements or object keys to exhaust memory during validation and terminate the process with JavaScript heap exhaustion.
Read the original description
The Model Context Protocol TypeScript SDK provides TypeScript client and server implementations of the Model Context Protocol. From 1.3.0 until 1.32.0 in @modelcontextprotocol/sdk and from 2.0.0 until 2.3.0 in @modelcontextprotocol/server, HTTP servers did not enforce a limit on the number of array elements and object keys validated in one request. The affected surface is validation of HTTP requests containing arrays or object keys. The trigger is an array-element or object-key validation workload large enough to exhaust memory while remaining within the request size limit. A single request within the default 4 MiB limit can terminate the process with JavaScript heap exhaustion. No credentials are required unless the application authenticates before SDK processing. Tools accepting arrays or records carry the greatest risk. stdio-only servers do not expose the HTTP request path. Upgrading alone does not enable the new validation bound. Operators must configure both a tool-input element bound and an appropriate request body size limit. This issue is fixed in @modelcontextprotocol/sdk 1.32.0 and @modelcontextprotocol/server 2.3.0.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure22/25Default setups, reachable over the network without a login
- Reach?/20Unknown. No tracked technology or package matched
- Severity7.5/10CVSS 7.5
- No patch0/5No signal
What would change the score
- Would score about 70 if added to CISA KEV
- Would score about 65 if CISA's SSVC rates exploitation active
What to do
Check every install: default setups are affected.
Upgrade to a fixed version: typescript-sdk 1.32.0 · server 2.3.0 · sdk 1.32.0.
Workaround: Set maxRequestBodySize on the transport or createMcpHandler() to a lower limit, and set maxToolInputElements on McpServer; or use a reverse proxy.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- modelcontextprotocol typescript-sdk
From 1.3.0 · fixed in 1.32.0
- @modelcontextprotocol server
From 2.0.0 · fixed in 2.3.0
- @modelcontextprotocol sdk
From 1.3.0 · fixed in 1.32.0
Evidence 7
- Advisory
- Repository
- Repository
- Repository
- Repository
Show all 7 sourcesShow fewer sources
- Repository
- Repository
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-111768
Is CVE-2026-111768 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
A single HTTP request within the default 4 MiB size limit can exhaust server memory during input validation. The Node process then aborts with JavaScript heap out of memory. The risk is highest for McpServer tools whose input contains an array or a record.Source: github.com
Which versions are affected by CVE-2026-111768?
typescript-sdk: from 1.3.0 before 1.32.0. server: from 2.0.0 before 2.3.0. sdk: from 1.3.0 before 1.32.0.Source: cve.now feed data
Am I affected, and how do I check?
Affected versions are @modelcontextprotocol/sdk 1.3.0 through 1.31.0 and @modelcontextprotocol/server 2.0.0 through 2.2.0. Only servers whose HTTP transport is reachable by clients not fully trusted are in scope; stdio-only servers are not affected. To check, look at the installed version of @modelcontextprotocol/sdk or @modelcontextprotocol/server in package.json or with npm ls.Source: github.com
How do I fix CVE-2026-111768?
Upgrade @modelcontextprotocol/sdk to 1.32.0 or later, or @modelcontextprotocol/server to 2.3.0 or later.Source: github.com