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8.3

Snap7 up to version 1.4.3 can be crashed by malformed data

CVE-2026-115723 · published 12 days ago
Summary

Snap7 versions up to 1.4.3 may let a malicious device on the network send specially crafted messages that overwrite memory. This can cause the software that controls industrial systems to stop working or behave incorrectly. Apply the vendor’s update or patch to prevent the malformed messages from being processed.

What to do

The CVE record does not list a fixed version. Check the vendor's site or the advisory links below - a fix may already be released.

Affected software
VendorProductAffected versions
davenardella snap7 <= 1.4.3
Original advisory text
Snap7 through 1.4.3 Out-of-Bounds Write via BRecv and CheckAsBRecvCompletion
Snap7 through 1.4.3 contains an out-of-bounds write vulnerability in the passive partner that allows a malicious active partner to overflow application buffers by declaring an unvalidated BSend total length. Attackers connecting from the configured peer address can declare up to 65535 bytes and send a short fragment, causing BRecv to memcpy past the buffer and crash or corrupt SCADA, HMI or gateway processes.
References
Fix within
Internet-facing 60 days
Internal At next upgrade
  • Not known to be exploited
  • Needs hands-on effort to exploit
  • Gives an attacker partial control
Severity
8.3 High
Exploitation
<1% chance of attack within 30 days
Type
CWE-787Out-of-bounds Write
Timeline
Published23 Oct 2026
Updated4 Nov 2026
First seen23 Oct 2026
Sources
CVE-2026-115723 · NVD
CVE-2026-115723 · MITRE
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