Full Report
SIMATIC S7-1500 devices contain multiple vulnerabilities in the web server that could allow an attacker to execute malicious code in an authorized user’s browser session and perform PLC operations within the scope of that user’s authorization. Siemens is preparing fixes and recommends specific mitigations for products where fixes are not or not yet available.
Analysis Summary
# Vulnerability: Multiple Web Server Vulnerabilities in SIMATIC S7-1500
## CVE Details
- **CVE ID:** CVE-2026-63350, CVE-2026-63351, CVE-2026-63352, CVE-2026-63353, CVE-2026-63354, CVE-2026-63355, CVE-2026-63356, CVE-2026-63357
- **CVSS Score:** 9.6 (Critical) [CVSS v3.1] / 9.4 (Critical) [CVSS v4.0]
- **CWE:** CWE-79 (Cross-site Scripting), CWE-120 (Buffer Copy without Checking Size of Input), CWE-20 (Improper Input Validation)
## Affected Systems
- **Products:**
- SIMATIC Drive Controller CPU 1504D TF & 1507D TF
- SIMATIC ET 200SP Open Controller CPU 1515SP PC2 (V2 & V3 CPUs)
- SIMATIC S7-1500 CPU Family
- **Versions:** All versions currently affected for the listed models.
- **Configurations:** Devices with the integrated Web Server enabled.
## Vulnerability Description
SIMATIC S7-1500 devices harbor multiple flaws within their integrated web server. These include:
1. **Memory Corruption:** Several CVEs (including 63350-63354) involve improper handling of specific web requests or file imports that can lead to buffer overflows or memory corruption.
2. **Cross-Site Scripting (XSS):** CVE-2026-63355, 63356, and 63357 involve a failure to sanitize input from imported CSV trace files or calculated signal names.
3. **Result:** If an authorized user is social-engineered into importing a malicious file or visiting a link, an attacker can execute arbitrary JavaScript in the user's browser session. This allows the attacker to perform PLC operations (e.g., stopping the CPU, changing configurations) using the victim's permissions.
## Exploitation
- **Status:** Not reported as exploited in the wild (as of advisory date).
- **Complexity:** Low to Medium (requires user interaction/social engineering for XSS).
- **Attack Vector:** Network (Remote)
## Impact
- **Confidentiality:** High (Session hijacking and data theft).
- **Integrity:** High (Ability to perform PLC operations and modify settings).
- **Availability:** High (Potential for Remote Code Execution or Denial of Service via memory corruption).
## Remediation
### Patches
- **Status:** Siemens is currently preparing fixes for the affected product families. No firmware patches are available at the time of this publication.
### Workarounds
- **Disable Web Server:** If not required, disable the web server functionality via the TIA Portal configuration.
- **Restrict Access:** Use firewalls or VPNs to ensure the web server is not accessible from untrusted networks or the internet.
- **User Training:** Caution users against importing CSV or trace files from untrusted sources.
- **Role-Based Access:** Apply the principle of least privilege for web server user accounts.
## Detection
- **Indicators of Compromise:** Unusual PLC configuration changes, unexpected CPU stop commands, or unauthorized login attempts in web server logs.
- **Detection Methods:** Monitor network traffic for malformed HTTP requests directed at the PLC. Use Industrial Intrusion Detection Systems (IDS) to flag suspicious file uploads (CSV/Trace) to SIMATIC devices.
## References
- Siemens ProductCERT Advisory: [https://cert-portal.siemens.com/productcert/html/ssa-591731.html](https://cert-portal.siemens.com/productcert/html/ssa-591731.html)
- Siemens CERT Advisories Main Page: [https://www.siemens.com/cert/advisories](https://www.siemens.com/cert/advisories)
- Siemens Terms of Use: [https://www.siemens.com/productcert/terms-of-use](https://www.siemens.com/productcert/terms-of-use)