Client crash via unchecked Upload response length
Published Sep 13, 2026 · Updated Sep 13, 2026
Memory corruption in Snap7 1.4.0 through 1.4.3 allows remote attackers to crash client applications via a crafted S7 Upload response. The TSnap7MicroClient::opUpload path subtracts a fixed header size from the server-supplied DataLen field and passes the unchecked signed result to memcpy without bounding it to received data or opData capacity. Exploitation requires a client application to initiate an upload from a malicious or compromised S7 server, and successful exploitation corrupts or over-reads client memory before the process crashes.
Summary
What happened
Memory corruption in Snap7 1.4.0 through 1.4.3 allows remote attackers to crash client applications via a crafted S7 Upload response. The TSnap7MicroClient::opUpload path subtracts a fixed header size from the server-supplied DataLen field and passes the unchecked signed result to memcpy without bounding it to received data or opData capacity. Exploitation requires a client application to initiate an upload from a malicious or compromised S7 server, and successful exploitation corrupts or over-reads client memory before the process crashes.
The record
- CVE
- CVE-2026-90572
- Published
- Sep 13, 2026
- Updated
- Sep 13, 2026
- Vendor
- Davide Nardella
- Product
- Snap7
- Classifications
- T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 13, 2026CVE publishedPublication date reported by the CVE source.
- Sep 13, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=1.4.0
- Affected versionversion=1.4.1
- Affected versionversion=1.4.2
- Affected versionversion=1.4.3
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Crafted S7 Upload response reproductionproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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