CVE-2026-76842 Mercado Pago Node.js SDK through 3.4.0 Path Injection via Unencoded Identifiers in Payment Clients
Attackers can manipulate payment identifiers to access or modify other merchant resources via path traversal in the Mercado Pago Node.js SDK.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-76842?
CVE-2026-76842 is a high-severity path traversal vulnerability in mercadopago, published on 24 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
The Mercado Pago Node.js SDK interpolates caller-supplied identifiers into API request paths without percent-encoding them, so characters that are structural in a URL survive into the outgoing request. The payment (get, capture, cancel), paymentRefund (create, total, list, get), advancedPayment (get, capture, cancel, update, updateReleaseDate) and disbursementRefund (create, createAll, listAll) clients build their path as a template literal, for example RestClient.fetch(`/v1/payments/${id}`, ...) in src/clients/payment/get/index.ts. A dot-dot or slash sequence in the identifier is normalised by the WHATWG URL parser and redirects the request to a different endpoint, and a question mark appends attacker-chosen query parameters, in both cases carrying the merchant's own access token. An application that forwards an identifier influenced by an untrusted party into one of these methods without an ownership check therefore allows that party to reach other resources within the merchant's token scope. The repository already contains the intended helper, encodePathParam in src/utils/path.ts, which pull request 451 applied to roughly 29 other clients while leaving these unchanged.
Weakness: CWE-22
Which versions are affected by CVE-2026-76842?
How do I fix CVE-2026-76842?
No fix has been published for CVE-2026-76842 yet. Limit exposure of the affected software until one is available.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-76842 being exploited?
There is no known exploitation of CVE-2026-76842 in the wild and no public exploit code.
Sources
Also known as GHSA-8vxq-h2gr-x277.