Client process crash via unbounded negotiated PDU length
Published Jul 19, 2026 · Updated Jul 19, 2026
Out-of-bounds write in Snap7 1.4.0 through 1.4.3 allows remote authenticated users to crash client processes via a malicious S7 peer. TSnap7Peer::NegotiatePDULength trusts the peer's uncapped length, and opWriteArea uses it to size a memcpy into a fixed 4096-byte payload. Exploitation requires control of the S7 peer or negotiation traffic and a subsequent sufficiently large WriteArea operation; the demonstrated result is client heap corruption and a process crash.
Summary
What happened
Out-of-bounds write in Snap7 1.4.0 through 1.4.3 allows remote authenticated users to crash client processes via a malicious S7 peer. TSnap7Peer::NegotiatePDULength trusts the peer's uncapped length, and opWriteArea uses it to size a memcpy into a fixed 4096-byte payload. Exploitation requires control of the S7 peer or negotiation traffic and a subsequent sufficiently large WriteArea operation; the demonstrated result is client heap corruption and a process crash.
The record
- CVE
- CVE-2026-16225
- Published
- Jul 19, 2026
- Updated
- Jul 19, 2026
- Vendor
- Davide Nardella
- Product
- Snap7
- Classifications
- CWE-119, CWE-787, T1499.004
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Jul 19, 2026CVE publishedPublication date reported by the CVE source.
- Jul 19, 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?
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
- Snap7 malicious S7 peer reproducerproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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