CVE-2023-51773Network attack vector

Memory disclosure or crash via APDU length underflow

Published Dec 25, 2023 · Updated Aug 2, 2024

Out-of-bounds read in BACnet Stack before 1.3.2 allows remote attackers to read memory or crash a process via a crafted APDU. The bacapp_decode_application_data function subtracts a decoded tag length from the unsigned APDU size without first proving that the tag fits within the supplied buffer, turning a truncated value into an oversized remaining-length bound. Any network-facing application or embedded device that links the affected decoder and processes attacker-controlled BACnet application data can expose adjacent memory or terminate; no integrity impact is reported.

CVSS severity9.1
Critical
EPSS probability1.05%
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 read in BACnet Stack before 1.3.2 allows remote attackers to read memory or crash a process via a crafted APDU. The bacapp_decode_application_data function subtracts a decoded tag length from the unsigned APDU size without first proving that the tag fits within the supplied buffer, turning a truncated value into an oversized remaining-length bound. Any network-facing application or embedded device that links the affected decoder and processes attacker-controlled BACnet application data can expose adjacent memory or terminate; no integrity impact is reported.

The record

CVE
CVE-2023-51773
Published
Dec 25, 2023
Updated
Aug 2, 2024
Vendor
BACnet Stack
Product
BACnet Protocol Stack
Classifications
CWE-126
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 25, 2023CVE 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=0 <1.3.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

BACnet Stack · BACnet Protocol Stackversion=0 <1.3.2

Published CVSS scores

9.1CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-126Buffer Over-read

Public exploit references

No public exploit references are available in this record.

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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