CVE-2026-62977
BACnet Stack: `WriteProperty(File_Size)` can bypass read-only protection and expose uninitialized RAMFS tail bytes through `AtomicReadFile`
Published Nov 13, 2026
CVSS 4.0 · 6.9 Medium
EPSS n/a
KEV · Not listed
Description
BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to version 1.5.1, the BACnet FILE object implementation allows remote WriteProperty(PROP_FILE_SIZE) requests to change the size of a stream-access FILE object without checking whether that FILE is marked Read_Only. When the FILE backend is RAMFS, enlarging the file only performs realloc() and updates the stored size; the newly exposed tail region is not initialized before later reads. As a result, a remote client can enlarge a read-only RAMFS-backed stream-access FILE and then immediately retrieve the newly exposed region with AtomicReadFile(stream-access). Depending on the allocator and build configuration, the returned data may contain sanitizer fill bytes, stale heap contents, or other unintended process memory. Shrinking the file through the same path can also remotely truncate content that was intended to be read-only. This issue has been patched in versions 1.5.1 and 1.6.0.
Affected Products
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CVE record
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NVD configurations
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Red Hat packages
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OpenCVE enrichment
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Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
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| bacnet-stack | bacnet-stack | affected |
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Remediation
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Metrics
Attack Vector Network
Attack Complexity Low
Privileges Required None
Attack Requirements None
User Interaction None
Vulnerable System Confidentiality Impact Low
Vulnerable System Integrity Impact Low
Vulnerable System Availability Impact None
Subsequent System Confidentiality Impact None
Subsequent System Integrity Impact None
Subsequent System Availability Impact None
No CVSS v3.1
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
No EPSS score available.
Key SSVC decision points have not yet been added.
References
History
Nov 13, 2026 6:45 PM
Description updated. Title updated. Weaknesses updated. Added references. Scoring metrics updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Description | BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to version 1.5.1, the BACnet FILE object implementation allows remote WriteProperty(PROP_FILE_SIZE) requests to change the size of a stream-access FILE object without checking whether that FILE is marked Read_Only. When the FILE backend is RAMFS, enlarging the file only performs realloc() and updates the stored size; the newly exposed tail region is not initialized before later reads. As a result, a remote client can enlarge a read-only RAMFS-backed stream-access FILE and then immediately retrieve the newly exposed region with AtomicReadFile(stream-access). Depending on the allocator and build configuration, the returned data may contain sanitizer fill bytes, stale heap contents, or other unintended process memory. Shrinking the file through the same path can also remotely truncate content that was intended to be read-only. This issue has been patched in versions 1.5.1 and 1.6.0. | |
| Title | BACnet Stack: `WriteProperty(File_Size)` can bypass read-only protection and expose uninitialized RAMFS tail bytes through `AtomicReadFile` | |
| Weaknesses | CWE-284 CWE-908 |
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cvssV4_0
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Subscriptions
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