bacnet-stack BACnet Stack up to 1.5.0.rc3 apps/readfile/main.c path traversal

CVSS Meta Temp Score
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CTI Interest Score
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6.8$0-$5k0.00

Summaryinfo

A vulnerability was found in bacnet-stack BACnet Stack up to 1.5.0.rc3. It has been rated as critical. Impacted is an unknown function of the file apps/readfile/main.c. Performing a manipulation results in path traversal. This vulnerability was named CVE-2026-21878. The attack may be initiated remotely. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as critical has been found in bacnet-stack BACnet Stack up to 1.5.0.rc3. This affects an unknown function of the file apps/readfile/main.c. The manipulation with an unknown input leads to a path traversal vulnerability. CWE is classifying the issue as CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. This is going to have an impact on integrity, and availability. The summary by CVE is:

BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.5.0.rc3, a vulnerability has been discovered in BACnet Stack's file writing functionality where there is no validation of user-provided file paths, allowing attackers to write files to arbitrary directories. This affects apps/readfile/main.c and ports/posix/bacfile-posix.c. This vulnerability is fixed in 1.5.0.rc3.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-21878 since 01/05/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1006 for this issue.

Upgrading to version 1.5.0.rc3 eliminates this vulnerability. Applying the patch c5dc00a77b4bc2550befa67a930b333e299c18f3 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Vendor

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.0
VulDB Meta Temp Score: 6.8

VulDB Base Score: 6.5
VulDB Temp Score: 6.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.5
CNA Vector (GitHub_M): 🔒

CVSSv2info

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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Path traversal
CWE: CWE-22
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: BACnet Stack 1.5.0.rc3
Patch: c5dc00a77b4bc2550befa67a930b333e299c18f3

Timelineinfo

01/05/2026 CVE reserved
02/13/2026 +39 days Advisory disclosed
02/13/2026 +0 days VulDB entry created
02/13/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: GHSA-p8rx-c26w-545j
Status: Confirmed

CVE: CVE-2026-21878 (🔒)
GCVE (CVE): GCVE-0-2026-21878
GCVE (VulDB): GCVE-100-345933

Entryinfo

Created: 02/13/2026 20:31
Changes: 02/13/2026 20:31 (67)
Complete: 🔍
Cache ID: 216::103

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