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Vulnerabilities

Vulnerability · CVE-2026-21878

BACnet Stack is a BACnet open source protocol stack C library for embedded systems.

Published Feb 13, 2026 · catalog updated Feb 13, 2026 · BACnet Stack is a

Last checked Nov 3, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-21878. EPSS is 0.41%. Act only if a listed version of BACnet Stack is a is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (BACnet Stack is a).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.41%
Remediation
Version ranges on file
Affected products
vendor bacnet-stack bacnet-stack < 1.5.0.rc3

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor bacnet-stack bacnet-stack < 1.5.0.rc3< 1.5.0.rc3

How to fix CVE-2026-21878

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-21878. EPSS is 0.41%. Act only if a listed version of BACnet Stack is a is installed.

Which versions are affected?

Compare what you have installed with bacnet-stack bacnet-stack < 1.5.0.rc3 < 1.5.0.rc3. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.41%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Feb 13, 2026 · EUVD

    Detected

    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

  2. Feb 13, 2026 · EUVD

    Updated

    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

Sources

  • FIRST EPSSExploitation probabilityCVE-2026-21878

    30-day exploitation probability 0.41%

    first.org
  • EUVDVulnerability recordEUVD-2026-6026

    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

    euvd.enisa.europa.eu

References

Freshness

Last verified in this catalog Nov 3, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSNov 3, 2026
  • EUVDNov 3, 2026