Bruno API Client EUVD-2026-71121

Exploitation requires that the victim user (1) imports a collection authored or modified by the attacker, and (2) actively executes that collection using the Bruno CLI or desktop application. The body:file feature must be used in the malicious request - this is a supported and commonly used Bruno feature, not a non-default configuration, so no special setup is required on the victim side. The attack is limited by the user-interaction requirement (the victim must run the collection) and by file-system permission boundaries (Bruno can only read files the victim's OS user account can read). Exploitation does not require any network service to be listening on the victim machine; the victim initiates the outbound HTTP connection that delivers the file to the attacker.

The provided CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N) scores 7.1 and accurately captures the core risk: network-distributable, low-complexity attack requiring only passive user interaction (running the collection) to achieve full confidentiality compromise of local files. The attack is essentially a malicious-collection supply-chain scenario - identical in class to malicious Postman or Insomnia collection attacks. Real-world risk is meaningful within developer and QA teams that routinely share collections, but is bounded by the user-interaction requirement (UI:P) and the product's relatively niche footprint. No public exploit code or CISA KEV listing is present, reducing urgency compared to mass-exploitation scenarios. The EPSS data is not provided, but given the niche audience and social-engineering precondition, widespread automated scanning exploitation is unlikely. The highest realistic threat is targeted developer workstation compromise or CI/CD pipeline infiltration via a shared collection repository.

An attacker publishes or shares a Bruno collection (e.g., via a GitHub repository, a developer forum, or a phishing link) that contains a GET or POST request with a body:file field set to ../../../../home/user/.ssh/id_rsa. When a developer imports and runs the collection - a routine action in API development workflows - Bruno reads the SSH private key and sends it as the request body to an attacker-controlled server. No authentication or elevated privilege is required on the victim's machine beyond the ability to run Bruno.