CVSS 3.1
6.5 mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:HCVE-2026-46677 BACnet Stack: Client-Side Out-of-Bounds Read in AtomicReadFile-ACK Record-Access Handling via RecordCount / fileData[] Mismatch
Medium (6.5) in bacnet-stack bacnet-stack. EPSS 0.2% estimated probability of exploitation activity in the next 30 days.
On this page
BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to versions 1.4.4 and 1.5.1, there is a client-side out-of-bounds read in the AtomicReadFile-ACK record-access handling path. The issue is caused by a mismatch between a remote returnedRecordCount value and the fixed local fileData[] array capacity in BACNET_ATOMIC_READ_FILE_DATA. The ACK decode path preserves the remote RecordCount, discards storage for excess records without truncating that count, and a downstream sink later iterates over the original RecordCount and indexes fileData[i] out of bounds. This issue has been patched in versions 1.4.4 and 1.5.1.
Severity
- EPSS
- 0.2% estimated probability of exploitation activity in the next 30 days; 12th percentile. Scored 2026-11-13. A forecast for this CVE across the internet, not for your own systems.
- CISA's assessment (SSVC)
- Exploitation: none · Automatable: no · Technical impact: partial, assessed 2026-11-13. From CISA's Vulnrichment in the CVE List: whether it is exploited, whether exploiting it can be automated, and how much control it gives.
- Published
- Modified
- Assigned by
- GitHub_M (CNA)
- NVD analysis
- Awaiting analysis
- Record from
- the NVD, synced
Ask an AI about this CVE
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Explain CVE-2026-46677 for an engineer deciding whether to act. Use https://cve.bz/api/public/cves/CVE-2026-46677?via=ask-ai-copy and https://cve.bz/cve/CVE-2026-46677?via=ask-ai-copy as the source of truth: what is affected and which versions fix it, whether it is in CISA KEV, public exploits, and its EPSS (an internet-wide 30-day estimate of exploitation activity, not a forecast for my systems). If they give no fixed versions, use the CVE record https://cveawg.mitre.org/api/cve/CVE-2026-46677 or the vendor advisory, not third-party mirrors. Tell me how to check whether I am affected and how to verify a fix. Cite the sources and say where they are uncertain.Opens a third-party assistant; its answer is its own, not cve.bz's. The prompt holds only this CVE's id and public links.
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Affected
Versions
From the CNA's record in the CVE List.
| Product | Affected |
|---|---|
| bacnet-stack | < 1.4.4 |
| bacnet-stack | < 1.5.1 |
Attack patterns (CAPEC)
- CAPEC-540 Overread Buffers Likelihood: Low · Severity: High
- CAPEC-47 Buffer Overflow via Parameter Expansion Likelihood: Medium · Severity: High
The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.