How severe is CVE-2021-27673?

CVE-2021-27673 has a CVSS score of 4.8/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2021-27673?

CVE-2021-27673 affects the following packages: tribalsystems/zenario (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2021-27673?

Update tribalsystems/zenario to 8.8.53370 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-27673 is resolved across your whole dependency graph.

How do I detect CVE-2021-27673 in my Packagist dependencies?

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

How do I mitigate CVE-2021-27673 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is CVE-2021-27673 actively exploited in the wild?

Yes. There are 2 known exploit references for CVE-2021-27673, including 2 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2021-27673?

CVE-2021-27673 has an EPSS (Exploit Prediction Scoring System) score of 1.1%, placing it in the 64th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-27673?

CVE-2021-27673 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2021-27673 published, and has it been updated?

CVE-2021-27673 was published on June 8, 2021 and was last updated on February 16, 2024. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘

🐘 Packagist

Not in CISA KEV

MEDIUM severity

CVE-2021-27673 — zenario

MEDIUM

CVE-2021-27673 is a medium-severity (CVSS 4.8) Cross-site Scripting (XSS) vulnerability in tribalsystems/zenario. 2 public exploit references exist, so weaponization risk is real. A fix is available for tribalsystems/zenario — see the affected versions and patch details below.

reflected XSS in tribalsystems/zenario

Published

Jun 8, 2021

Updated

Feb 16, 2024

Affected

1 pkg

Patched

1 / 1

Exploits

2 known

Exploitation data as of Oct 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.1%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs64th percentile — riskier than 64% of all scored CVEsHighest risk

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

How urgent is this, really

CVE-2021-27673 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 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

🐘tribalsystems/zenario

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

Cross Site Scripting (XSS) in the "admin_boxes.ajax.php" component of Tribal Systems Zenario CMS v8.8.52729 allows remote attackers to execute arbitrary code by injecting arbitrary HTML into the "cID" parameter when creating a new HTML component.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`tribalsystems/zenario`	all versions	8.8.53370`composer require tribalsystems/zenario:^8.8.53370`

Affected Products

1 product · 1 configurations

Application

zenariotribalsystems

1 version

8.8.52729

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Cross Site Scripting (XSS) in the "admin_boxes.ajax.php" component of Tr…

deadsh0t.medium.comNVDJun 2021

Cross Site Scripting (XSS) in the "admin_boxes.ajax.php" component of Tr…

packetstormsecurity.comNVDMay 2022

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for tribalsystems/zenario, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update tribalsystems/zenario to 8.8.53370 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-27673 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

Reflected XSS in the "admin_boxes.ajax.php" component of Tribal Systems Zenario CMS v8.8.52729 allows remote attackers to execute arbitrary code by injecting into the "cID" parameter when creating a new HTML component.

O3 Security · Impact-Aware SCA

Is CVE-2021-27673 in your dependencies?

Find it across Packagist, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

4.8/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

High

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Raw vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N

CWE Classification

CWE-79Cross-site Scripting (XSS)

Weaponization

No known public exploit tooling found.

Timeline

Disclosed

Jun 8, 2021

First exploit

Jun 11, 2021

3 days after disclosure — rapid exploitation

Last updated

Feb 16, 2024

Identifiers

CVE-2021-27673

References

Advisorynvd.nist.gov Webdeadsh0t.medium.com Webgithub.com Webpacketstormsecurity.com Packagegithub.com

Related vulnerabilities

This CVE is medium severity; 6 of 8 other CVEs affecting tribalsystems/zenario are rated as high or higher (top: critical).

CVE-2024-45964CVE-2024-45960CVE-2024-34460CVE-2024-34461CVE-2023-44769CVE-2023-44771CVE-2023-44770CVE-2022-44136

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedFeb 16, 2024