CVE-2023-26793Public exploitNetwork attack vector

Test-client crash via undersized destination buffer

Published May 1, 2024 · Updated Aug 2, 2024

A reported heap buffer overflow in libmodbus 3.1.10 allows remote attackers to crash the bundled unit-test client with a crafted Modbus reply. The test requests UT_BITS_NB+1 results after allocating tab_rp_bits for only UT_BITS_NB bytes, so read_io_status writes past the caller-owned buffer. Debian classifies the assignment as bogus because the undersized destination belongs to the test case, leaving no demonstrated flaw in correctly calling applications.

CVSS severity9.8
Critical
EPSS probability0.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A reported heap buffer overflow in libmodbus 3.1.10 allows remote attackers to crash the bundled unit-test client with a crafted Modbus reply. The test requests UT_BITS_NB+1 results after allocating tab_rp_bits for only UT_BITS_NB bytes, so read_io_status writes past the caller-owned buffer. Debian classifies the assignment as bogus because the undersized destination belongs to the test case, leaving no demonstrated flaw in correctly calling applications.

The record

CVE
CVE-2023-26793
Published
May 1, 2024
Updated
Aug 2, 2024
Vendor
Stéphane Raimbault
Product
libmodbus
Classifications
CWE-122
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 1, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 2, 2024Record 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=3.1.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Stéphane Raimbault · libmodbusversion=3.1.0

Published CVSS scores

9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-122Heap-based Buffer Overflow

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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