How severe is CVE-2021-33988?

CVE-2021-33988 has a CVSS score of 6.1/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2021-33988?

CVE-2021-33988 affects the following packages: microweber/microweber (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2021-33988?

Update microweber/microweber to 1.2.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-33988 is resolved across your whole dependency graph.

How do I detect CVE-2021-33988 in my Packagist dependencies?

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

How do I mitigate CVE-2021-33988 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-2021-33988 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2021-33988, including 1 in-the-wild exploitation 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-2021-33988?

CVE-2021-33988 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-2021-33988?

CVE-2021-33988 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-2021-33988 published, and has it been updated?

CVE-2021-33988 was published on October 19, 2021 and was last updated on August 7, 2026. 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-2021-33988 — microweber

MEDIUM

CVE-2021-33988 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in microweber/microweber. 1 public exploit reference exists, so weaponization risk is real. A fix is available for microweber/microweber — see the affected versions and patch details below.

Cross Site Scripting in Microweber

Also known asGHSA-w7x8-cq7r-g5g9

Published

Oct 19, 2021

Updated

Aug 7, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

Exploitation data as of Oct 6, 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-2021-33988 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,386 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

🐘microweber/microweber

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). vulnerability exists in Microweber CMS 1.2.7 via the Login form, which could let a malicious user execute Javascript by Inserting code in the request form.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`microweber/microweber`	all versions	1.2.8`composer require microweber/microweber:^1.2.8`

Affected Products

1 product · 1 configurations

Application

microwebermicroweber

1 version

1.2.7

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). vulnerability exists in Microweber CMS 1.2.7…

github.comNVDOct 2021

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for microweber/microweber, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update microweber/microweber to 1.2.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-33988 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

Cross Site Scripting (XSS). vulnerability exists in Microweber CMS 1.2.7 via the Login form, which could let a malicious user execute Javascript by Inserting code in the request form.

O3 Security · Impact-Aware SCA

Is CVE-2021-33988 in your dependencies?

Find it across Packagist, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

6.1/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Raw vector

CVSS:3.1/AV:N/AC:L/PR:N/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

Oct 19, 2021

First exploit

Oct 20, 2021

1 day after disclosure — rapid exploitation

Last updated

Aug 7, 2026

Identifiers

CVE-2021-33988

GHSA-w7x8-cq7r-g5g9

References

Advisorynvd.nist.gov Packagegithub.com Evidencegithub.com

Related vulnerabilities

This CVE is medium severity; 5 of 8 other CVEs affecting microweber/microweber are rated as high or higher (top: moderate).

CVE-2026-12198CVE-2025-70791CVE-2025-70792CVE-2025-51504CVE-2025-51501CVE-2025-51502CVE-2025-51503CVE-2025-34076

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedAug 7, 2026