PatchSiren cyber security CVE debrief

CVE-2026-25786 Cert Portal CVE debrief

CVE-2026-25786 is a critical web-interface scripting issue affecting multiple Siemens SIMATIC and S7-1500 family devices. The advisory says PLC/station names rendered on the "communication" parameters page are not properly validated or sanitized, allowing an authenticated attacker who can download a TIA project to inject malicious scripts. If another user with appropriate rights opens that page, the script runs inside that user's web session. The source advisory was published on 2026-05-12 and republished by CISA on 2026-05-14. Vendor fixes exist for many affected models, while some entries are marked as having no fix planned or no fix available, so access restriction is an important interim control.

Vendor: Cert Portal
Product: Siemens SIMATIC Drive Controller CPU 1504D TF (6ES7615-4DF10-0AB0) vers:intdot/<3.1.6 SIMATIC Drive Controller CPU 1507D TF (6ES7615-7DF10-0AB0) SIMATIC ET 200SP CPU 1510SP F-1 PN (6ES7510-1SJ00-0AB0) vers:all/* SIMATIC ET 200SP CPU 1510SP F-1 PN (6ES7510-1SJ01-0AB0) vers:intdot/<2.9.9 SIMATIC ET 200SP CPU 1510SP F-1 PN (6ES7510-1SK03-0AB0) SIMATIC ET 200SP CPU 1510SP-1 PN (6ES7510-1DJ00-0AB0) SIMATIC ET 200SP CPU 1510SP-1 PN (6ES7510-1DJ01-0AB0) SIMATIC ET 200SP CPU 1510SP-1 PN (6ES7510-1DK03-0AB0) SIMATIC ET 200SP CPU 1512SP F-1 PN (6ES7512-1SK00-0AB0) SIMATIC ET 200SP CPU 1512SP F-1 PN (6ES7512-1SK01-0AB0) SIMATIC ET 200SP CPU 1512SP F-1 PN (6ES7512-1SM03-0AB0) SIMATIC ET 200SP CPU 1512SP-1 PN (6ES7512-1DK00-0AB0) SIMATIC ET 200SP CPU 1512SP-1 PN (6ES7512-1DK01-0AB0) SIMATIC ET 200SP CPU 1512SP-1 PN (6ES7512-1DM03-0AB0) SIMATIC ET 200SP CPU 1514SP F-2 PN (6ES7514-2SN03-0AB0) SIMATIC ET 200SP CPU 1514SP-2 PN (6ES7514-2DN03-0AB0) SIMATIC ET 200SP CPU 1514SPT F-2 PN (6ES7514-2WN03-0AB0) SIMATIC ET 200SP CPU 1514SPT-2 PN (6ES7514-2VN03-0AB0) SIMATIC ET 200SP Open Controller CPU 1515SP PC (incl. SIPLUS variants) SIMATIC ET 200SP Open Controller CPU 1515SP PC2 (incl. SIPLUS variants) V2 CPUs SIMATIC ET 200SP Open Controller CPU 1515SP PC2 (incl. SIPLUS variants) V3 CPUs SIMATIC ET 200SP Open Controller CPU 1515SP PC3 V4 CPUs SIMATIC S7-1500 CPU 1511-1 PN (6ES7511-1AK00-0AB0) SIMATIC S7-1500 CPU 1511-1 PN (6ES7511-1AK01-0AB0) SIMATIC S7-1500 CPU 1511-1 PN (6ES7511-1AK02-0AB0) SIMATIC S7-1500 CPU 1511-1 PN (6ES7511-1AL03-0AB0) SIMATIC S7-1500 CPU 1511C-1 PN (6ES7511-1CK00-0AB0) SIMATIC S7-1500 CPU 1511C-1 PN (6ES7511-1CK01-0AB0) SIMATIC S7-1500 CPU 1511C-1 PN (6ES7511-1CL03-0AB0) SIMATIC S7-1500 CPU 1511F-1 PN (6ES7511-1FK00-0AB0) SIMATIC S7-1500 CPU 1511F-1 PN (6ES7511-1FK01-0AB0) SIMATIC S7-1500 CPU 1511F-1 PN (6ES7511-1FK02-0AB0) SIMATIC S7-1500 CPU 1511F-1 PN (6ES7511-1FL03-0AB0) SIMATIC S7-1500 CPU 1511T-1 PN (6ES7511-1TK01-0AB0) SIMATIC S7-1500 CPU 1511T-1 PN (6ES7511-1TL03-0AB0) SIMATIC S7-1500 CPU 1511TF-1 PN (6ES7511-1UK01-0AB0) SIMATIC S7-1500 CPU 1511TF-1 PN (6ES7511-1UL03-0AB0) SIMATIC S7-1500 CPU 1512C-1 PN (6ES7512-1CK00-0AB0) SIMATIC S7-1500 CPU 1512C-1 PN (6ES7512-1CK01-0AB0) SIMATIC S7-1500 CPU 1512C-1 PN (6ES7512-1CM03-0AB0) SIMATIC S7-1500 CPU 1513-1 PN (6ES7513-1AL00-0AB0) SIMATIC S7-1500 CPU 1513-1 PN (6ES7513-1AL01-0AB0) SIMATIC S7-1500 CPU 1513-1 PN (6ES7513-1AL02-0AB0) SIMATIC S7-1500 CPU 1513-1 PN (6ES7513-1AM03-0AB0) SIMATIC S7-1500 CPU 1513F-1 PN (6ES7513-1FL00-0AB0) SIMATIC S7-1500 CPU 1513F-1 PN (6ES7513-1FL01-0AB0) SIMATIC S7-1500 CPU 1513F-1 PN (6ES7513-1FL02-0AB0) SIMATIC S7-1500 CPU 1513F-1 PN (6ES7513-1FM03-0AB0) SIMATIC S7-1500 CPU 1513pro F-2 PN (6ES7513-2GM03-0AB0) SIMATIC S7-1500 CPU 1513pro-2 PN (6ES7513-2PM03-0AB0) SIMATIC S7-1500 CPU 1515-2 PN (6ES7515-2AM00-0AB0) SIMATIC S7-1500 CPU 1515-2 PN (6ES7515-2AM01-0AB0) SIMATIC S7-1500 CPU 1515-2 PN (6ES7515-2AM02-0AB0) SIMATIC S7-1500 CPU 1515-2 PN (6ES7515-2AN03-0AB0) SIMATIC S7-1500 CPU 1515F-2 PN (6ES7515-2FM00-0AB0) SIMATIC S7-1500 CPU 1515F-2 PN (6ES7515-2FM01-0AB0) SIMATIC S7-1500 CPU 1515F-2 PN (6ES7515-2FM02-0AB0) SIMATIC S7-1500 CPU 1515F-2 PN (6ES7515-2FN03-0AB0) SIMATIC S7-1500 CPU 1515T-2 PN (6ES7515-2TM01-0AB0) SIMATIC S7-1500 CPU 1515T-2 PN (6ES7515-2TN03-0AB0) SIMATIC S7-1500 CPU 1515TF-2 PN (6ES7515-2UM01-0AB0) SIMATIC S7-1500 CPU 1515TF-2 PN (6ES7515-2UN03-0AB0) SIMATIC S7-1500 CPU 1516-3 PN/DP (6ES7516-3AN00-0AB0) SIMATIC S7-1500 CPU 1516-3 PN/DP (6ES7516-3AN01-0AB0) SIMATIC S7-1500 CPU 1516-3 PN/DP (6ES7516-3AN02-0AB0) SIMATIC S7-1500 CPU 1516-3 PN/DP (6ES7516-3AP03-0AB0) SIMATIC S7-1500 CPU 1516F-3 PN/DP (6ES7516-3FN00-0AB0) SIMATIC S7-1500 CPU 1516F-3 PN/DP (6ES7516-3FN01-0AB0) SIMATIC S7-1500 CPU 1516F-3 PN/DP (6ES7516-3FN02-0AB0) SIMATIC S7-1500 CPU 1516F-3 PN/DP (6ES7516-3FP03-0AB0) SIMATIC S7-1500 CPU 1516pro F-2 PN (6ES7516-2GP03-0AB0) SIMATIC S7-1500 CPU 1516pro-2 PN (6ES7516-2PP03-0AB0) SIMATIC S7-1500 CPU 1516T-3 PN (6ES7516-3TP10-0AB0) SIMATIC S7-1500 CPU 1516T-3 PN/DP (6ES7516-3TN00-0AB0) SIMATIC S7-1500 CPU 1516TF-3 PN (6ES7516-3UP10-0AB0) SIMATIC S7-1500 CPU 1516TF-3 PN/DP (6ES7516-3UN00-0AB0)
CVSS: CRITICAL 9.1
CISA KEV: Not listed in stored evidence
Original CVE published: 2026-05-12
Original CVE updated: 2026-05-14
Advisory published: 2026-05-12
Advisory updated: 2026-05-14

Who should care

OT security teams, Siemens SIMATIC/S7-1500 operators, PLC administrators, and anyone who manages TIA project downloads or uses the affected web interface should treat this as relevant. It is especially important for environments where multiple users have access to the communication parameters page or where higher-privilege engineering accounts can upload project data.

Technical summary

The issue is a script injection problem in the device web UI: user-controlled PLC/station names are rendered on the communication parameters page without proper validation/sanitization. The attacker must already be authenticated and authorized to download a TIA project into the product, which matches the supplied CVSS vector's high privileges requirement. Once a crafted name is stored, any legitimate user who opens the page can trigger script execution in the context of their web session. This aligns with CWE-79 (cross-site scripting) and the supplied CVSS 3.1 vector AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H.

Defensive priority

Immediate

Recommended defensive actions

Apply the Siemens vendor fix for the exact affected model and firmware/software branch referenced in the advisory; the remediation set includes V3.1.6 or later for some products and V2.9.9 or later for others.
Restrict TIA project download capability to trusted personnel only, as explicitly recommended in the advisory.
Limit access to the device web interface and the communication parameters page to the smallest practical administrative group.
Treat PLC/station names as untrusted input and ensure any web rendering uses validation plus context-appropriate output encoding/sanitization.
Review OT web-session logging and access patterns for unexpected script behavior or unauthorized changes to station naming data.

Evidence notes

The source corpus is the CISA CSAF republication of Siemens ProductCERT advisory SSA-688146 for ICSA-26-134-15. Its revision history shows initial publication on 2026-05-12 and CISA republication on 2026-05-14. The advisory text states that PLC/station names on the "communication" parameters page are not properly validated/sanitized and can be used to inject malicious scripts that execute when a benign user accesses the page. The remediation section shows a mixed status across products: vendor fixes for some models, while others are marked "currently no fix planned" or "currently no fix is available." No KEV listing or ransomware-use signal is present in the supplied data.

Official resources

Published 2026-05-12 and republished 2026-05-14. The supplied data does not list a KEV entry or known ransomware campaign use.