CVE-2026-15105Public exploit

Server crash via misbudgeted ReadVar response assembly

Published Jul 8, 2026 · Updated Jul 8, 2026

Out-of-bounds write in Snap7 1.4.0 through 1.4.3 allows remote attackers on the local network to crash a Snap7 server via ReadVar. TS7Worker::PerformFunctionRead budgets only raw item data, but ReadArea copies data after uncounted headers and padding into the fixed TS7Answer23 stack buffer. An unauthenticated S7 connection and a registered readable area are sufficient; the demonstrated multi-item request overwrites adjacent stack state and terminates the server.

CVSS severity6.3
Medium
EPSS probability0.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in Snap7 1.4.0 through 1.4.3 allows remote attackers on the local network to crash a Snap7 server via ReadVar. TS7Worker::PerformFunctionRead budgets only raw item data, but ReadArea copies data after uncounted headers and padding into the fixed TS7Answer23 stack buffer. An unauthenticated S7 connection and a registered readable area are sufficient; the demonstrated multi-item request overwrites adjacent stack state and terminates the server.

The record

CVE
CVE-2026-15105
Published
Jul 8, 2026
Updated
Jul 8, 2026
Vendor
Davide Nardella
Product
Snap7
Classifications
CWE-787, CWE-119, T1499.004
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 8, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 8, 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.

  1. Affected versionversion=1.4.0
  2. Affected versionversion=1.4.1
  3. Affected versionversion=1.4.2
  4. Affected versionversion=1.4.3

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Davide Nardella · Snap7version=1.4.0; version=1.4.1; version=1.4.2; version=1.4.3

Published CVSS scores

6.3VulDBCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
2.1VulDBCVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
5.8VulDBAV:A/AC:L/Au:N/C:P/I:P/A:P

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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

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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