Vulnerability · Published Feb 13, 2026 · Assigned by GitHub_M
CVE-2026-26264BACnet Stack WriteProperty decoding length underflow leads to OOB read and crash
High 7.8
In plain English
A high-severity out-of-bounds read in bacnet-stack from bacnet-stack. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 37% of all known vulnerabilities).
Official 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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| bacnet-stack | bacnet-stack | >= 1.5.0rc1, < 1.5.0rc4< 1.4.3rc2 |
Weakness: CWE-125 · Vector: 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