CVE-2026-41503: BACnet Stack is a BACnet open source protocol stack C library for embedded systems

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HIGH 7.5REMOTEUPGRADE

CVE-2026-41503 is a high-severity flaw (CVSS 7.5) affecting bacnet stack. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.4.3, an out-of-bounds read vulnerability in bacnet-stack's ReadPropertyMultiple service property decoder allows unauthenticated remote attackers to read past allocated buffer boundaries by sending an RPM request with a truncated property list. The vulnerability stems from rpm_decode_object_property() calling the deprecated decode_tag_number_and_value()

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 64%)
CISA exploited list	No
Weakness	CWE-125
Published	2026-04-24
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: bacnetstack

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-24 20:16 UTCPublished CVE record published
2026-06-17 10:46 UTCUpdated Record last modified

bacnetstack bacnet stack UPGRADE

Affected: >= 1.4.0 and < 1.4.3 · 1.5.0 rc1

Fixed in: 1.4.3

Safe to downgrade to: a release before 1.4.0

1. Check installed version

apt-cache policy bacnet-stack || rpm -q bacnet-stack || bacnet-stack --version

2. UPGRADE to 1.4.3 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade bacnet-stack

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade bacnet-stack

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 1.4.0 (Debian / Ubuntu)

apt-cache madison bacnet-stack sudo apt install bacnet-stack=<VERSION_BEFORE_1.4.0> sudo apt-mark hold bacnet-stack

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list bacnet-stack sudo dnf downgrade bacnet-stack-<VERSION_BEFORE_1.4.0> sudo dnf versionlock add bacnet-stack

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-41503?

bacnet stack: upgrade to 1.4.3. Exact commands for each OS are on this page.

Is CVE-2026-41503 being exploited?

CVE-2026-41503 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-41503 affect?

CVE-2026-41503 affects bacnet stack. Severity is high (CVSS 7.5). BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.4.3, an out-of-bounds read vulnerability in bacnet-stack's ReadPropertyMultiple service property decoder allows unauthenticated remote attackers

How urgent is CVE-2026-41503?

Priority 45/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-41502 HIGH 7.5 UPGRADE BACnet Stack is a BACnet open source protocol stack C library for embedded systems
CVE-2026-41475 CRITICAL 9.1 UPGRADE BACnet Stack is a BACnet open source protocol stack C library for embedded systems
CVE-2026-40279 LOW 3.7 UPGRADE BACnet Stack is a BACnet open source protocol stack C library for embedded systems

References

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