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Not in CISA KEV
HIGH severity

CVE-2021-41243 — basercms

HIGHFix: baserproject/basercms@9088b99

CVE-2021-41243 is a high-severity (CVSS 8.8) OS Command Injection vulnerability in baserproject/basercms. A fix is available for baserproject/basercms — see the affected versions and patch details below.

OS Command Injection Vulnerability and Potential Zip Slip Vulnerability in baserCMS

Also known asGHSA-7rpc-9m88-cf9w
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Oct 12, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
2.2%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs82th percentile — riskier than 82% of all scored CVEsHighest risk
1.67%2.21%2.76%3.30%2.8%2.8%2.2%2.2%May 26Oct 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-41243 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,987 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
🐘baserproject/basercms

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

There is a Potential Zip Slip Vulnerability and OS Command Injection Vulnerability on the management system of baserCMS. Users with permissions to upload files may upload crafted zip files which may execute arbitrary commands on the host operating system. This is a vulnerability that needs to be addressed when the management system is used by an unspecified number of users. If you are eligible, please update to the new version as soon as possible.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐘Packagistbaserproject/basercmsall versions4.5.4composer require baserproject/basercms:^4.5.4

Affected Products

1 product · 1 configurations
Application
basercmsbasercms
< 4.5.4
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for baserproject/basercms, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update baserproject/basercms to 4.5.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-41243 is resolved across your whole dependency graph.

  3. Workarounds

    Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

Frequently Asked Questions

There is a Potential Zip Slip Vulnerability and OS Command Injection Vulnerability on the management system of baserCMS. Users with permissions to upload files may upload crafted zip files which may execute arbitrary commands on the host operating system. This is a vulnerability that needs to be addressed when the management system is used by an unspecified number of users. If you are eligible, please update to the new version as soon as possible.
O3 Security · Impact-Aware SCA

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CVE-2021-41243: basercms — Fixed in 4.5.4