Out-of-bounds Read in Bacnet-Stack
CVE-2026-26264
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.
Vulnerability class: Buffer Overflow
EPSS: 0.004 (29.7th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H.
Affected products
- Bacnet-stack — versions >= 1.5.0rc1, < 1.5.0rc4, < 1.4.3rc2
- Bacnetstack Bacnet_stack — versions 1.4.3, 1.5.0
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Exploit, Vendor Advisory)
- security-advisories@github.com (Patch, x_refsource_MISC)
Frequently asked questions
- What is CVE-2026-26264?
- CVE-2026-26264 is a high-severity vulnerability in Bacnet-Stack, classified under Out-of-bounds Read. CVSS score: 8.1/10. Published 2026-02-13.
- How severe is CVE-2026-26264?
- High severity. CVSS v3 base score is 8.1 out of 10.