PT-2026-8018 · Unknown · Bacnet Protocol Stack

Finder16 · Published 2026-02-13 · Updated 2026-02-13 · CVE-2026-21870

Positive Technologies (AI Summary)

CVSS v3.1

5.5

Medium

Base vector

AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Name of the Vulnerable Software and Affected Versions BACnet Protocol Stack versions 1.4.2 and 1.5.0.rc2 and earlier

Description The BACnet Protocol Stack library contains a flaw in the ubasic interpreter due to an off-by-one stack-based buffer overflow. This occurs when processing string literals that exceed the buffer limit. The tokenizer string function in src/bacnet/basic/program/ubasic/tokenizer.c incorrectly manages null termination for strings at the maximum length, leading to a stack overflow and a crash.

Recommendations Versions prior to 1.5.0.rc2 should be updated.

Exploit

Fix

Weakness Enumeration

CWE-193

Related Identifiers

CVE-2026-21870

GHSA-PC83-WP6W-93MX

Affected Products

Bacnet Protocol Stack

References · 8

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/21xxx/CVE-2026-21870.json · Exploit
• 🔥 https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-pc83-wp6w-93mx · Exploit
• https://github.com/bacnet-stack/bacnet-stack/pull/1196 · Patch
• https://github.com/bacnet-stack/bacnet-stack/commit/4e1176394a5ae50d2fd0b5790d9bff806dc08465 · Patch
• https://osv.dev/vulnerability/CVE-2026-21870 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-21870 · Security Note
• https://twitter.com/CVEnew/status/2022387982230262120 · Twitter Post
• https://twitter.com/VulmonFeeds/status/2022384259814609074 · Twitter Post