CVE-2026-55787

Deferred Deferred - Pending Action

Flyto2 Core URL Validation SSRF via IPv4-Mapped Addresses

Publication date: 2026-10-14

Last updated on: 2026-10-15

Assigner: GitHub, Inc.

Description

Flyto2 Core is an execution kernel for automation and AI-agent workflows. Prior to 2.26.3, validate_url_ssrf and is_private_ip in src/core/utils.py compare resolved addresses only against native private IPv4 and IPv6 ranges and do not unwrap IPv4-mapped, IPv4-compatible, 6to4, or NAT64 transition addresses. An authenticated workflow author can provide a transition-form literal URL through the Execution API POST /v1/execute route, http.get, or sibling guarded outbound-request modules, causing the guard to accept an address whose embedded IPv4 points to loopback, RFC 1918, or cloud metadata services. On a host that routes the selected transition form, the outbound request reaches the internal destination and returns the response body to the workflow caller, enabling read SSRF and disclosure of internal-service data or cloud credentials. This issue is fixed in version 2.26.3.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-10-14

Last Modified

2026-10-15

Generated

2026-10-19

AI Q&A

2026-10-15

EPSS Evaluated

2026-10-18

NVD

CVE-2026-55787

EUVD

EUVD-2026-101588

Affected Vendors & Products

Vendor	Product	Version / Range
flytohub	flyto-core	< 2.26.3

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-918	The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.

Attack-Flow Graph

Executive Summary

CVE-2026-55787 is a Server-Side Request Forgery (SSRF) vulnerability in the Flyto2 Core automation kernel. It affects versions before 2.26.3 where the SSRF guard fails to properly validate IPv6 transition addresses like IPv4-mapped or NAT64 formats. These addresses embed IPv4 or loopback targets that bypass private IP checks, allowing attackers to access internal services or cloud metadata endpoints through crafted URLs.

Detection Guidance

To detect this vulnerability, check if your flyto-core version is below 2.26.3. Use commands like 'pip show flyto-core' or inspect version in package files. Monitor outbound requests for IPv6 transition addresses (e.g., ::ffff:127.0.0.1) targeting internal services or cloud metadata endpoints.

Impact Analysis

An authenticated workflow author can exploit this to make outbound requests to internal services like cloud metadata endpoints or loopback addresses. The attacker receives responses containing sensitive data such as internal-service responses or cloud credentials, enabling data exfiltration or unauthorized access to restricted resources.

Compliance Impact

This SSRF vulnerability could lead to unauthorized access to sensitive data, violating confidentiality requirements in GDPR and HIPAA. Exposure of cloud metadata or internal services may result in breaches of data protection regulations, potentially leading to legal penalties and compliance failures.

Mitigation Strategies

Upgrade flyto-core to version 2.26.3 or later immediately. Apply the patch from the official repository or PyPI. Review workflow configurations for suspicious URLs using IPv6 transition formats. Restrict outbound requests to trusted destinations.

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