How severe is CVE-2017-6099?

CVE-2017-6099 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-2017-6099?

CVE-2017-6099 affects the following packages: paypal/merchant-sdk-php (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2017-6099?

Update paypal/merchant-sdk-php to 3.12.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2017-6099 is resolved across your whole dependency graph.

How do I detect CVE-2017-6099 in my Packagist dependencies?

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

How do I mitigate CVE-2017-6099 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-2017-6099 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2017-6099, 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-2017-6099?

CVE-2017-6099 has an EPSS (Exploit Prediction Scoring System) score of 1.2%, placing it in the 69th 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-2017-6099?

CVE-2017-6099 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-2017-6099 published, and has it been updated?

CVE-2017-6099 was published on February 24, 2017 and was last updated on October 20, 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-2017-6099 — merchant-sdk-php

MEDIUM

CVE-2017-6099 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in paypal/merchant-sdk-php. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for paypal/merchant-sdk-php — see the affected versions and patch details below.

PayPal PHP Merchant SDK Cross-site scripting (XSS) vulnerability

Also known asGHSA-p4g7-wjhq-9r2h

Published

Feb 24, 2017

Updated

Oct 20, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs69th percentile — riskier than 69% of all scored CVEsHighest risk

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

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

🐘paypal/merchant-sdk-php

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 in GetAuthDetails.html.php in PayPal PHP Merchant SDK (aka merchant-sdk-php) 3.9.1 allows remote attackers to inject arbitrary web script or HTML via the token parameter.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`paypal/merchant-sdk-php`	≥ 3.0.0&&< 3.12.0	3.12.0`composer require paypal/merchant-sdk-php:^3.12.0`

Affected Products

1 product · 1 configurations

Application

merchant-sdk-phppaypal

1 version

3.9.1

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 in GetAuthDetails.html.php in P…

github.comNVDMar 2019

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for paypal/merchant-sdk-php, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update paypal/merchant-sdk-php to 3.12.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2017-6099 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

O3 Security · Impact-Aware SCA

Is CVE-2017-6099 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:3.0/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 Nuclei template or Metasploit module yet. 1 public proof-of-concept reference is listed on this page.

Timeline

Disclosed

Feb 24, 2017

First exploit

Mar 13, 2019

Last updated

Oct 20, 2026

Identifiers

CVE-2017-6099

GHSA-p4g7-wjhq-9r2h

References

Advisorysecurityfocus.com Advisorynvd.nist.gov · CVE 2017 6099 Webgithub.com · CVE 2017 6099.yaml Evidencegithub.com

Related vulnerabilities

This CVE is medium severity; 8 of 8 other CVEs with CWE-79 are rated as high or higher (top: critical).

CVE-2026-113787CVE-2026-44267CVE-2026-96632CVE-2026-9086CVE-2026-118246CVE-2026-118251CVE-2026-118253CVE-2026-116797Browse all CWE-79

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedOct 20, 2026