CVE-2026-107194

Executive Summary

CVE-2026-107194 is an authentication bypass vulnerability in Sungrow iSolarCloud (versions before 2026) that permits account takeover by submitting a crafted login request containing "login_type":"5". The flaw requires only the victim's email address—which an attacker can obtain by viewing the email associated with their own parent organization—enabling unauthenticated, remote compromise of arbitrary accounts. Because iSolarCloud manages distributed solar power infrastructure across Europe, successful mass exploitation could disrupt grid operations at scale, with the NVD description warning of potential "local blackouts on the whole continent."

Technical Analysis

The vulnerability is classified as CWE-288: Authentication Bypass Using an Alternate Path or Channel. In iSolarCloud's login flow, the authentication routine processes a login_type parameter that selects among multiple authentication pathways. When login_type is set to "5", the application appears to route the login request through an alternate authentication channel that does not enforce the standard credential verification controls. The result is that a valid password, token, or second factor is not required to complete authentication for a targeted account.

The attack requires two preconditions, both of which are low-friction:

1. Knowledge of the target email address. The NVD description states the user_account property of the request must contain an email address. Critically, the description notes that "a user can view the email address associated with their parent organization." This means an attacker who holds any low-privileged account within a parent organization can enumerate the email addresses of accounts in that organizational hierarchy and then pivot to authenticate as those users.

2. Reachability of the iSolarCloud login endpoint. iSolarCloud is a cloud-hosted platform, so the attack surface is internet-facing by default. No local network access, no user interaction, and no pre-existing credentials beyond a single low-privilege account are needed.

The login_type parameter is a client-controlled value in the login request body. Because the server trusted this field to select the authentication mechanism, an attacker can force the application down a code path whose authorization checks are absent, incomplete, or assume the caller has already been validated. This is the canonical "alternate path" pattern in CWE-288: the primary login route enforces MFA/password checks, but the login_type:5 path does not.

No public proof-of-concept code, Nuclei template, or exploit module was observed at the time of this report. The precise structure of the alternate authentication path (token issuance, session creation, or API key generation) is not documented in available sources, so the exact post-authentication artifact an attacker receives cannot be confirmed. The vulnerability class—forced selection of an unguarded authentication branch—is sufficient to explain the account-takeover outcome.

Exploitation Scenarios

No public PoC is available; the attack chain below is inferred from the vulnerability class (CWE-288) and the parameters explicitly named in the NVD description.

1. Reconnaissance and target identification. The attacker registers or obtains a low-privileged iSolarCloud account that belongs to a parent organization. Using the platform's organization view, the attacker enumerates email addresses associated with that parent organization. Because the vulnerable login path only requires an email address (user_account) and does not require the target's password, email enumeration alone is sufficient to select victims. No scanning of the internet is required—the target set is drawn from the attacker's own organizational visibility.

2. Triggering the flaw. The attacker issues a login request to the iSolarCloud authentication endpoint with the body containing "login_type":"5" and the user_account property set to the victim's email address. Because the server routes this request to the alternate authentication channel, the normal credential-verification step is skipped. The attacker is not required to supply a password, one-time code, or pre-shared secret for the victim account.

3. Session establishment. On success, the application returns a session or token bound to the victim's identity. The attacker is now authenticated as the victim user, inheriting that user's role and permissions within iSolarCloud. No exploit payload, malformed input, or memory-corruption primitive is needed—this is a logic/authorization flaw, not a code-execution flaw.

4. Post-exploitation impact. From the victim's account, the attacker gains the victim's level of access to solar generation, inverter, and grid-management functions. If the compromised account holds operational privileges (e.g., a utility or aggregator administrator), the attacker could issue control commands affecting connected generation assets. The NVD description explicitly frames the worst-case impact as "local blackouts on the whole continent" in Europe, indicating that the blast radius extends from individual accounts to grid stability. Persistence is achievable by creating additional accounts or API tokens, and lateral movement within the organization hierarchy is enabled by the same email-visibility primitive used during reconnaissance.

Impact Assessment

The CVSS vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H reflects a maximum-severity profile: network-exploitable, low complexity, no privileges required, no user interaction, changed scope, and high confidentiality, integrity, and availability impact.

• Confidentiality (High): Attackers obtain full access to victim accounts, including the organization's user directory, plant topology, and operational data.
• Integrity (High): Authenticated attackers can modify configurations and potentially issue control commands to generation assets.
• Availability (High): Manipulation of grid-connected solar infrastructure can cause service disruption, up to and including regional blackouts as described.
• Scope (Changed): Compromise of the cloud platform propagates to physical energy infrastructure—a clear crossing of security boundaries.

Blast radius: iSolarCloud is a multi-tenant platform serving residential, commercial, and utility-scale solar operators. A single exploitable authentication bypass that scales via email enumeration threatens every account in an affected tenant hierarchy. If an attacker reaches accounts with grid-interconnection privileges, the impact is not limited to data loss—it extends to electrical grid stability across a continent. The CVSS score is N/A in the provided intelligence data; EPSS has not yet been scored by FIRST.org, and the CVE is not in CISA KEV. Absence of a score should not be read as low risk; the UNPATCHED status and physical-infrastructure impact argue for treating this as critical regardless of scoring gaps.

Detection Guidance

Sigma Rule

title: Sungrow iSolarCloud Authentication Bypass via login_type 5
id: 8f3a2c91-4d7e-4b6a-9c1f-2e5b8a7d6f01
status: experimental
description: Detects login requests to iSolarCloud using the alternate authentication path (login_type 5) associated with CVE-2026-107194 authentication bypass.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-107194
author: valtersit.com Threat Intelligence
date: 2026/01/01
logsource:
  product: webserver
  service: http
detection:
  selection_uri:
    cs-uri-stem|contains:
      - '/login'
      - '/oauth'
      - '/api/login'
  selection_body:
    cs-uri-query|contains: 'login_type=5'
  selection_body_json:
    - 'login_type":"5'
    - 'login_type": "5'
  condition: selection_uri and (selection_body or selection_body_json)
falsepositives:
  - Legitimate use of login_type 5 by the iSolarCloud mobile application (validate against vendor documentation)
level: critical
tags:
  - attack.t1190
  - attack.initial_access
  - cve.2026.107194

YARA Rule

rule CVE_2026_107194_iSolarCloud_AuthBypass
{
    meta:
        description = "Detects HTTP request bodies attempting the iSolarCloud login_type=5 authentication bypass (CVE-2026-107194)"
        author = "valtersit.com Threat Intelligence"
        date = "2026-01-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-107194"
        severity = "critical"

    strings:
        $login_type_a = "\"login_type\":\"5\"" ascii nocase
        $login_type_b = "\"login_type\": \"5\"" ascii nocase
        $user_account = "\"user_account\"" ascii nocase
        $login_path   = "/login" ascii nocase
        $isolar       = "iSolarCloud" ascii nocase

    condition:
        (uint16(0) == 0x4854 or $login_path or $isolar) and
        ($login_type_a or $login_type_b) and
        $user_account
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2026-107194 Sungrow iSolarCloud Authentication Bypass login_type 5"; flow:established,to_server; http.method; content:"POST"; http.uri; content:"login"; nocase; http.request_body; content:"\"login_type\""; nocase; http.request_body; content:"\"5\""; nocase; http.request_body; content:"user_account"; nocase; classtype:attempted-admin; reference:cve,2026-107194; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-107194; sid:2026107194; rev:1; metadata:created_at 2026_01_01, updated_at 2026_01_01;)

Elastic Detection

sequence by source.ip with maxspan=30s
  [network where network.protocol == "http" and http.request.method == "POST" and
     url.path : "*login*" and http.request.body.text : "*login_type*5*"]
  [network where network.protocol == "http" and http.request.method == "POST" and
     url.path : "*login*" and http.request.body.text : "*user_account*"]

Splunk SPL Query

index=web OR index=proxy sourcetype=access_combined OR sourcetype=stream:http
| eval login_type = if(match(_raw, "\"?login_type\"?\s*[:=]\s*\"?5\"?"), 1, 0)
| eval has_user_account = if(match(_raw, "user_account"), 1, 0)
| eval is_login_uri = if(match(uri_path, "(?i)(login|oauth|api/login)"), 1, 0)
| where login_type=1 AND has_user_account=1 AND is_login_uri=1
| stats count min(_time) as first_seen max(_time) as last_seen by src_ip, uri_path, user_account
| convert ctime(first_seen) ctime(last_seen)
| sort - count

Wazuh OSSEC Rule

<group name="solarweb,isolarcloud,cve-2026-107194,">
  <rule id="2026107" level="12">
    <decoded>json</decoded>
    <field name="login_type">^5$</field>
    <description>CVE-2026-107194: Sungrow iSolarCloud authentication bypass attempt using login_type=5</description>
    <options>no_full_log</options>
  </rule>
  <rule id="2026108" level="13">
    <if_sid>2026107</if_sid>
    <field name="user_account">\.</field>
    <description>CVE-2026-107194: iSolarCloud auth bypass with target user_account supplied (possible account takeover)</description>
    <mitre>
      <id>T1190</id>
    </mitre>
    <group>attack,initial_access,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 — UNPATCHED. No vendor fix, workaround, or tracked patch source was identified in available intelligence. The following measures are independent of a vendor patch.

1. Immediate mitigations

• Block or reject login_type:5 at the edge. Where an application-layer inline control (WAF/reverse proxy) permits inspection of request bodies, reject login requests containing "login_type":"5" on the iSolarCloud login route. This is a stopgap—it relies on an undocumented, server-trusted parameter and can be bypassed by alternate encodings, so treat it as detection-plus-delay, not a fix.
• Restrict email visibility in the organization hierarchy. The bypass depends on obtaining the target email via parent-organization visibility. Tighten role permissions so that low-privileged users cannot enumerate sibling or parent-organization account emails.
• Enforce a second factor at the identity layer. Remote-access and platform administration should require phishing-resistant MFA (hardware keys) that is validated independently of the login_type branch. A flawed alternate auth channel cannot be relied upon to enforce MFA; validating MFA outside the vulnerable code path contains the impact.
• Network isolation of control functions. Segregate grid-control APIs from the general web application so that a compromised GUI account does not automatically grant control-plane authority.

2. Patch/upgrade steps

• No patched version exists as of this report. Monitor the vendor's security advisory channel for a Sungrow iSolarCloud fix and apply it immediately upon release.
• If Sungrow issues a firmware/cloud update: apply, verify login behavior for login_type handling is corrected, and re-test that standard password/MFA paths are enforced for all account types.
• Maintain an inventory of all iSolarCloud accounts and tenant hierarchies so remediation can be validated account by account.

3. Long-term hardening

• Treat grid-interconnected cloud platforms as critical infrastructure: apply zero-trust principles to all authentication paths and require independent authorization checks per branch.
• Eliminate client-controlled selection of authentication mechanisms. The authenticated channel must never be selected by a caller-supplied parameter; only server-side identity assertions should decide which path runs.
• Implement comprehensive logging of login requests (source IP, login_type, user_account, outcome) and alert on anomalous login_type values.
• Conduct threat modeling of the full organization-hierarchy data model, since cross-tenant data exposure was the reconnaissance enabler.
• Adopt continuous CVE monitoring; because EPSS and CVSS data may lag, treat unpatched, unauthenticated, remotely exploitable flaws as critical by default.

References

• NVD — CVE-2026-107194: https://nvd.nist.gov/vuln/detail/CVE-2026-107194
• MITRE CWE-288 — Authentication Bypass Using an Alternate Path or Channel: https://cwe.mitre.org/data/definitions/288.html
• MITRE ATT&CK T1190 — Exploit Public-Facing Application: https://attack.mitre.org/techniques/T1190/
• Sungrow iSolarCloud product/security information: https://www.sungrowpower.com/
• CISA Known Exploited Vulnerabilities catalog (CVE-2026-107194 not currently listed): https://www.cisa.gov/known-exploited-vulnerabilities-catalog
• FIRST.org EPSS (CVE-2026-107194 not yet scored): https://www.first.org/epss/