How severe is CVE-2021-33903?

CVE-2021-33903 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-33903 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (61st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-33903?

CVE-2021-33903 primarily affects Lancom-systems Lcos. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-33903?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-33903 published?

CVE-2021-33903 was published on 2021-10-07 and last updated on 2026-06-17.

CVE-2021-33903

CVE-2021-33903 is a high-severity vulnerability in Lancom-systems Lcos with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 8.5
EPSS exploit prediction: 1% (61st percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Lancom-systems Lcos
Published: 2021-10-07
Last modified: 2026-06-17

Description

In LCOS 10.40 to 10.42.0473-RU3 with SNMPv3 enabled on LANCOM devices, changing the password of the root user via the CLI does not change the password of the root user for SNMPv3 access. (However, changing the password of the root user via LANconfig does change the password of the root user for SNMPv3 access.)

Frequently asked questions

What is CVE-2021-33903?: In LCOS 10.40 to 10.42.0473-RU3 with SNMPv3 enabled on LANCOM devices, changing the password of the root user via the CLI does not change the password of the root user for SNMPv3 access. (However, changing the password of the root user via LANconfig does change the password of the root user for SNMPv3 access.)
How severe is CVE-2021-33903?: CVE-2021-33903 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-33903 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (61st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-33903?: CVE-2021-33903 primarily affects Lancom-systems Lcos. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-33903?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-33903 published?: CVE-2021-33903 was published on 2021-10-07 and last updated on 2026-06-17.

References

https://www.nmedv.de/wp-content/uploads/2021/10/NME-2021-001.txt

Affected products (5)

cpe:2.3:o:lancom-systems:lcos:*:*:*:*:*:*:*:*
cpe:2.3:o:lancom-systems:lcos:10.42.0473:-:*:*:*:*:*:*
cpe:2.3:o:lancom-systems:lcos:10.42.0473:release_update1:*:*:*:*:*:*
cpe:2.3:o:lancom-systems:lcos:10.42.0473:release_update2:*:*:*:*:*:*
cpe:2.3:o:lancom-systems:lcos:10.42.0473:release_update3:*:*:*:*:*:*

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