CVE-2026-26264
BACnet Stack WriteProperty decoding length underflow leads to OOB read and crash
- State
- Published
- Severity
- 7.8 High
- Published
- Feb 13, 2026
- Updated
- Feb 13, 2026
- Reserved
- Feb 12, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 7.8 High | 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 | GitHub_M |
Weaknesses
- CWE-125 Out-of-bounds Read
Affected Products
| Product | Versions |
|---|---|
bacnet-stackbacnet-stack |
|
References
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