CVE intelligence and bounded remediation

CVE-2021-40358 — Siemens Simatic Pcs 7 security vulnerability

Critical CVSS 9.9

A vulnerability has been identified in SIMATIC PCS 7 V8.2 (All versions), SIMATIC PCS 7 V9.0 (All versions < V9.0 SP3 UC04), SIMATIC PCS 7 V9.1 (All versions < V9.1 SP1), SIMATIC WinCC V15 and earlier (All versions < V15 SP1 Update 7), SIMATIC WinCC V16 (All versions < V16 Update 5), SIMATIC WinCC V17 (All versions < V17 Update 2), SIMATIC WinCC V7.4 (All versions < V7.4 SP1 Update 19), SIMATIC WinCC V7.5 (All versions < V7.5 SP2 Update 5). Legitimate file operations on the web server of the affected systems do not properly neutralize special elements within the pathname. An attacker could then cause the pathname to resolve to a location outside of the restricted directory on the server and read, write or delete unexpected critical files.

Severity
Critical
CVSS
9.9 (3.1)
Published
2021-11-09
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-22

Affected products

  • siemens / simatic_pcs_7 / 8.2
  • siemens / simatic_pcs_7 / 9.0
  • siemens / simatic_pcs_7 / 9.1
  • siemens / simatic_wincc / 7.4

Showing 4 representative product identities from 48 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Path traversal, unsafe upload, and file handling

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Trace untrusted filenames, archive entries, URLs, and path segments into read, write, include, extraction, and upload operations.
  • Identify filesystem roots, mount permissions, symbolic-link behavior, archive handling, and whether uploaded content is web-accessible or executable.
  • Review canonicalization and containment checks across supported operating systems and storage backends.

Remediate safely

  • Generate server-side storage identifiers and resolve paths beneath a fixed root using filesystem-aware containment checks.
  • Reject absolute, parent-relative, alternate-separator, device, link, and archive entries that escape the intended root.
  • Store uploads outside executable or served paths, validate type and size, and use private atomic temporary files.

Authoritative sources

Complete CVE record and remediation plan

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