CVE-2026-55787

Name of the Vulnerable Software and Affected Versions flyto-core (affected versions not specified)

Description An issue exists in the Server-Side Request Forgery (SSRF) protection mechanism within src/core/utils.py. The is private ip() function and validate url ssrf guard only check for native RFC 1918, loopback, link-local, and unique-local IP ranges. This allows a workflow author to bypass the protection by using IPv6 transition address forms that embed IPv4 targets, such as IPv4-mapped (::ffff:a.b.c.d), IPv4-compatible (::a.b.c.d), 6to4 (2002::/16), and NAT64 prefixes (64:ff9b::/96 and 64:ff9b:1::/48).

An attacker can use the url parameter in the POST /v1/execute endpoint or within workflow YAML nodes to drive authenticated requests to internal-only destinations. This can lead to the exfiltration of sensitive data, such as IAM credentials from cloud instance-metadata services (e.g., 169.254.169.254) or access to internal loopback services. The vulnerability affects multiple atomic modules, including http.get, http.request, http.batch, http.paginate, http.session, browser.goto, image.download, communication.webhook trigger, notification.send, vector.connector, and llm.chat.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.

As a temporary mitigation, restrict the use of the url parameter in the affected API endpoints and atomic modules to prevent requests to IPv6 transition-form addresses.