CVE-2021-28911: BAB TECHNOLOGIE GmbH eibPort V3 prior version 3.9.1 allow unauthenticated attackers access to /tmp path which

Q: How do I fix CVE-2021-28911?

eibport firmware: upgrade to 3.9.1. Exact commands for each OS are on this page.

Q: Is CVE-2021-28911 being exploited?

CVE-2021-28911 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-28911 affect?

CVE-2021-28911 affects eibport firmware. Severity is critical (CVSS 9.8). BAB TECHNOLOGIE GmbH eibPort V3 prior version 3.9.1 allow unauthenticated attackers access to /tmp path which contains some sensitive data (e.g. device serial number). Having those info, a possible loginId can be self-calculated in a brute

Q: How urgent is CVE-2021-28911?

Priority 58/100. Critical severity; Remotely exploitable, no login, no user action

This month

CRITICAL 9.8REMOTEUPGRADE

CVE-2021-28911 is a critical-severity flaw (CVSS 9.8) affecting eibport firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

BAB TECHNOLOGIE GmbH eibPort V3 prior version 3.9.1 allow unauthenticated attackers access to /tmp path which contains some sensitive data (e.g. device serial number). Having those info, a possible loginId can be self-calculated in a brute force attack against BMX interface. This is usable and part of an attack chain to gain SSH root access.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.7% (top 23%)
CISA exploited list	No
Weakness	CWE-307, CWE-863
Published	2021-09-09
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: bab-technologie

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

Am I affected?

Timeline

2021-09-09 18:15 UTCPublished CVE record published
2026-06-17 03:47 UTCUpdated Record last modified

bab-technologie eibport firmware UPGRADE

Affected: < 3.9.1

Fixed in: 3.9.1

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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-2021-28911?

eibport firmware: upgrade to 3.9.1. Exact commands for each OS are on this page.

Is CVE-2021-28911 being exploited?

CVE-2021-28911 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-2021-28911 affect?

CVE-2021-28911 affects eibport firmware. Severity is critical (CVSS 9.8). BAB TECHNOLOGIE GmbH eibPort V3 prior version 3.9.1 allow unauthenticated attackers access to /tmp path which contains some sensitive data (e.g. device serial number). Having those info, a possible loginId can be self-calculated in a brute

How urgent is CVE-2021-28911?

Priority 58/100. Critical severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2021-28914 MEDIUM 6.5 UPGRADE BAB TECHNOLOGIE GmbH eibPort V3 prior version 3.9.1 allow the user to set a weak password because the strength
CVE-2021-28913 CRITICAL 9.8 UPGRADE BAB TECHNOLOGIE GmbH eibPort V3 prior version 3.9.1 allow unauthenticated attackers access to /webif/SecurityM
CVE-2021-28912 HIGH 7.2 UPGRADE BAB TECHNOLOGIE GmbH eibPort V3
CVE-2021-28910 HIGH 7.5 UPGRADE BAB TECHNOLOGIE GmbH eibPort V3 prior version 3.9.1 contains basic SSRF vulnerability
CVE-2021-28909 CRITICAL 9.8 UPGRADE BAB TECHNOLOGIE GmbH eibPort V3 prior version 3.9.1 allow unauthenticated attackers to access uncontrolled the

References

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