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CVE-2026-100403

HIGHCVSS 7.5/10

Last modified

CVE-2026-100403 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to versions 1.4.6, 1.5.2, and 1.6.1, the BACnet/SC hub's Linux WebSocket server reassembles fragmented WebSocket messages into a per-connection fragment_buffer.

Description

BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to versions 1.4.6, 1.5.2, and 1.6.1, the BACnet/SC hub's Linux WebSocket server reassembles fragmented WebSocket messages into a per-connection fragment_buffer. It grows that buffer with realloc() on every non-final frame, with no upper bound. A peer that streams binary continuation fragments and never sets FIN keeps the hub reallocating until the box runs out of memory or the process is OOM-killed. The buffer starts at the maximum legal BVLC-SC NPDU size, but nothing after that ties its growth back to that limit. This issue has been patched in versions 1.4.6, 1.5.2, 1.6.1, and 1.7.0.

Metrics

CVSS 3.1
7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
bacnet-stackbacnet-stack< 1.4.6; >= 1.5.0, < 1.5.2; >= 1.6.0, < 1.6.1

References

Timeline

Published
Last Modified
Status
Awaiting Analysis

Frequently Asked Questions

What is CVE-2026-100403?
BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to versions 1.4.6, 1.5.2, and 1.6.1, the BACnet/SC hub's Linux WebSocket server reassembles fragmented WebSocket messages into a per-connection fragment_buffer. It grows that buffer with realloc() on every non-final frame, with no upper bound. A peer that streams binary continuation fragments and never sets FIN keeps the hub reallocating until the box runs out of memory or the process is OOM-killed. The buffer starts at the maximum legal BVLC-SC NPDU size, but nothing after that ties its growth back to that limit. This issue has been patched in versions 1.4.6, 1.5.2, 1.6.1, and 1.7.0.
How severe is CVE-2026-100403?
CVE-2026-100403 has a CVSS score of 7.5/10 (HIGH severity).
How do I fix CVE-2026-100403?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST