How severe is CVE-2026-21861?

CVE-2026-21861 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-21861 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (81st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-21861?

CVE-2026-21861 affects Basercms. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-21861?

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

Does CVE-2026-21861 have an EU (EUVD) identifier?

Yes. CVE-2026-21861 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-17255.

When was CVE-2026-21861 published?

CVE-2026-21861 was published on 2026-03-31 and last updated on 2026-06-17.

CVE-2026-21861

CVE-2026-21861 is a critical-severity vulnerability in Basercms with a CVSS 3.x base score of 9.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-78.

Key facts

Severity: Critical (CVSS 3.x base score 9.1)
EPSS exploit prediction: 2% (81st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-17255
Weakness: CWE-78
Affected product: Basercms
Published: 2026-03-31
Last modified: 2026-06-17

Description

baserCMS is a website development framework. Prior to version 5.2.3, baserCMS contains an OS command injection vulnerability in the core update functionality. An authenticated administrator can execute arbitrary OS commands on the server due to improper handling of user-controlled input that is directly passed to exec() without sufficient validation or escaping. This issue has been patched in version 5.2.3.

Frequently asked questions

What is CVE-2026-21861?: baserCMS is a website development framework. Prior to version 5.2.3, baserCMS contains an OS command injection vulnerability in the core update functionality. An authenticated administrator can execute arbitrary OS commands on the server due to improper handling of user-controlled input that is directly passed to exec() without sufficient validation or escaping. This issue has been patched in version 5.2.3.
How severe is CVE-2026-21861?: CVE-2026-21861 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-21861 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (81st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-21861?: CVE-2026-21861 affects Basercms. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-21861?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-21861 have an EU (EUVD) identifier?: Yes. CVE-2026-21861 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-17255.
When was CVE-2026-21861 published?: CVE-2026-21861 was published on 2026-03-31 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:basercms:basercms:*:*:*:*:*:*:*:*

More vulnerabilities in Basercms

CVE-2026-30880 — Critical (CVSS 9.8): baserCMS is a website development framework. Prior to version 5.2.3, baserCMS has an OS command injection vulnerability…
CVE-2026-27697 — Critical (CVSS 9.8): baserCMS is a website development framework. Prior to version 5.2.3, baserCMS has a SQL injection vulnerability in blog…
CVE-2023-43792 — Critical (CVSS 9.8): baserCMS is a website development framework. In versions 4.6.0 through 4.7.6, there is a Code Injection vulnerability…
CVE-2023-25655 — Critical (CVSS 9.8): baserCMS is a Content Management system. Prior to version 4.7.5, any file may be uploaded on the management system of…
CVE-2023-25654 — Critical (CVSS 9.8): baserCMS is a Content Management system. Prior to version 4.7.5, there is a Remote Code Execution (RCE) Vulnerability…
CVE-2017-10842 — Critical (CVSS 9.8): SQL injection vulnerability in the baserCMS 3.0.14 and earlier, 4.0.5 and earlier allows remote attackers to execute…

All CVEs affecting Basercms →

Other CWE-78 (OS Command Injection) vulnerabilities

CVE-2026-56004 — Critical (CVSS 10.0): A shellcode injection in the mercurial handler of the obs tar_scm source service before version 0.12.4 could be used by…
CVE-2026-56415 — Critical (CVSS 10.0): Storage Concentrator (SC & SCVM) contains a command injection vulnerability within the debug.pl script that is…
CVE-2026-56413 — Critical (CVSS 10.0): Storage Concentrator (SC & SCVM) contains a command injection vulnerability in the ms_service.pl service, which listens…
CVE-2026-49869 — Critical (CVSS 10.0): Kestra is an open-source, event-driven orchestration platform. Prior to 1.0.45 and 1.3.21, AuthenticationFilter in…
CVE-2026-49261 — Critical (CVSS 10.0): MariaDB server is a community developed fork of MySQL server. Versions 10.6.1 through 10.6.26, 10.11.1 through…
CVE-2026-10520 — Critical (CVSS 10.0): An OS Command Injection vulnerability in Ivanti Sentry before the R10.5.2, R10.6.2 and R10.7.1 versions allows a…

Browse all CWE-78 (OS Command Injection) vulnerabilities →