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CVE-2026-26264— BACnet Stack WriteProperty decoding length underflow leads to OOB read and crash

Quick assessment

Affected
bacnet-stack bacnet-stack
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

BACnet Stack是BACnet Stack开源的一个适用于嵌入式系统、Linux、MacOS、BSD 和 Windows 的 BACnet 开源协议栈 C 库。 BACnet Stack 1.5.0rc4之前版本和1.4.3rc2之前版本存在缓冲区错误漏洞，该漏洞源于处理格式错误的WriteProperty请求时可能触发长度下溢，导致越界读取和崩溃。

AI Predicted 5.3 Difficulty: Moderate EPSS 0.56% · P44

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-26264

Vulnerability Information
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Vulnerability Title
BACnet Stack WriteProperty decoding length underflow leads to OOB read and crash
Source: CVE Program / CVE List V5
Vulnerability Description
BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.5.0rc4 and 1.4.3rc2, a malformed WriteProperty request can trigger a length underflow in the BACnet stack, leading to an out‑of‑bounds read and a crash (DoS). The issue is in wp.c within wp_decode_service_request. When decoding the optional priority context tag, the code passes apdu_len - apdu_size to bacnet_unsigned_context_decode without validating that apdu_size <= apdu_len. If a truncated APDU reaches this path, apdu_len - apdu_size underflows, resulting in a large size being used for decoding and an out‑of‑bounds read. This vulnerability is fixed in 1.5.0rc4 and 1.4.3rc2.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:H/SC:N/SI:N/SA:N/E:P
Source: CVE Program / CVE List V5
Vulnerability Type
跨界内存读
Source: CVE Program / CVE List V5
Vulnerability Title
BACnet Stack 缓冲区错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
BACnet Stack是BACnet Stack开源的一个适用于嵌入式系统、Linux、MacOS、BSD 和 Windows 的 BACnet 开源协议栈 C 库。 BACnet Stack 1.5.0rc4之前版本和1.4.3rc2之前版本存在缓冲区错误漏洞，该漏洞源于处理格式错误的WriteProperty请求时可能触发长度下溢，导致越界读取和崩溃。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
bacnet-stack bacnet-stack >= 1.5.0rc1, < 1.5.0rc4 -

II. Public POCs for CVE-2026-26264

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III. Intelligence Information for CVE-2026-26264

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Vendor Advisories for CVE-2026-26264 (1)

Same Patch Batch · bacnet-stack · 2026-02-13 · 3 CVEs total

CVE-2026-21878 7.5 HIGH BACnet Stack Improperly Limits Pathnames to a Restricted Directory
CVE-2026-21870 5.5 MEDIUM The BACnet Protocol Stack library has an Off-by-one Stack-based Buffer Overflow in tokeniz

IV. Related Vulnerabilities

Same product: bacnet-stack
Same vendor: bacnet-stack
Same weakness: CWE-125

V. Comments for CVE-2026-26264

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