CVE-2025-7770: Tigo Energy CCA Auth Bypass Vulnerability

CVE-2025-7770 Overview

CVE-2025-7770 affects the Tigo Energy Cloud Connect Advanced (CCA) device, a gateway used in solar optimization deployments. The vulnerability stems from insecure session identifier generation in the device's remote API. Session IDs are derived from the current timestamp using a predictable algorithm, allowing attackers to recreate valid session values. The flaw is compounded by the ability to bypass session ID requirements for specific commands. Combined, these issues enable unauthorized access to sensitive device functions on connected solar optimization systems. The weakness maps to [CWE-337] Predictable Seed in Pseudo-Random Number Generator.

Critical Impact
Network attackers with low privileges can predict valid session IDs and execute privileged commands on Tigo Energy CCA devices, compromising confidentiality, integrity, and availability of solar optimization infrastructure.

Affected Products

Tigo Energy Cloud Connect Advanced (CCA) device
CCA remote API endpoints
Connected solar optimization systems managed by the CCA gateway

Discovery Timeline

2025-08-06 - CVE-2025-7770 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-7770

Vulnerability Analysis

The Tigo Energy CCA device exposes a remote API that issues session identifiers to authenticated callers. These identifiers govern access to subsequent privileged commands. The implementation derives session IDs from the current system timestamp using a deterministic algorithm. An attacker who can approximate the timestamp at session creation can enumerate and reproduce valid session IDs within a narrow window. The device further weakens the model by accepting certain commands without enforcing a valid session ID at all. Together, the predictable identifier generation and inconsistent session validation create a reliable path to unauthorized control of solar optimization functions exposed by the CCA gateway.

Root Cause

The root cause is insufficient entropy in session token generation. The API uses the current timestamp as the primary seed material rather than a cryptographically secure pseudo-random number generator (CSPRNG). Timestamps are low-entropy, monotonically increasing, and partially observable to network attackers. A secondary defect is the omission of session validation on selected command handlers, which allows session-protected operations to be invoked without a valid token.

Attack Vector

An attacker with network reach to the CCA remote API and a low-privileged foothold can carry out the attack. The adversary records or estimates the timestamp at which a legitimate session was created, then iterates candidate timestamps through the predictable generation function to derive valid session IDs. The attacker replays the derived ID against the remote API to invoke privileged commands. For command handlers that skip session validation entirely, no session ID prediction is required. Successful exploitation grants unauthorized access to device management functions and the connected solar optimization equipment.

No public proof-of-concept exploit is currently associated with this CVE. Technical details are described in the CISA ICS Advisory ICSA-25-217-02.

Detection Methods for CVE-2025-7770

Indicators of Compromise

Repeated authentication or session establishment requests to the CCA remote API from a single source within short time windows, indicating brute-force or timestamp enumeration attempts.
Privileged API commands issued from sessions that were not preceded by a normal authentication flow.
Unexpected configuration changes or command executions on CCA devices outside of operator maintenance windows.

Detection Strategies

Inspect CCA device logs for sequential session ID requests or anomalous session lifetimes that diverge from normal operator behavior.
Correlate source IP addresses, user agents, and timing of API calls to identify automated session ID prediction tooling.
Monitor egress and ingress traffic to CCA management interfaces for connections from sources not on an approved operator allowlist.

Monitoring Recommendations

Forward CCA API access logs and operational telemetry to a centralized SIEM or data lake for correlation with network and identity events.
Establish baselines for typical CCA session counts, command frequency, and source addresses, and alert on deviations.
Track changes to solar optimizer setpoints, inverter commands, and firmware operations issued through the CCA API.

How to Mitigate CVE-2025-7770

Immediate Actions Required

Restrict network exposure of the CCA remote API to trusted management networks using firewall rules, ACLs, or VPN segmentation.
Disable or block remote API access from the public internet until a vendor fix is applied.
Rotate any operator credentials used with CCA devices and audit recent administrative activity for anomalies.
Review CISA advisory ICSA-25-217-02 for vendor-specific guidance and patch availability.

Patch Information

Refer to the CISA ICS Advisory ICSA-25-217-02 for vendor-provided remediation instructions and fixed firmware versions. Apply Tigo Energy updates as soon as they are released for affected CCA devices.

Workarounds

Place CCA devices behind a network segmentation boundary that limits API access to a small set of trusted management hosts.
Enforce VPN or zero-trust network access in front of the CCA management interface to prevent direct network reachability.
Monitor and rate-limit requests to the CCA remote API at an upstream proxy or firewall to slow session ID enumeration attempts.

bash

# Example iptables rules restricting CCA API access to a trusted management subnet
iptables -A INPUT -p tcp --dport 443 -s 10.10.50.0/24 -d <CCA_DEVICE_IP> -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -d <CCA_DEVICE_IP> -j DROP