Sybre Waaijer

Sybre Waaijer is a security researcher credited with 5 disclosed vulnerabilities in the WordSec WordPress vulnerability database, ranked #857 of 3,878 contributors. Their disclosures were published between 2018 and 2026. The most productive year was 2019, with 2 findings.

Their research concentrates on Cross-Site Scripting, which accounts for 2 of their findings (40%). Other recurring categories include Authorization Bypass Through User-Controlled Key, Missing Authorization. The average CVSS score across these disclosures is 6.0, peaking at 6.8.

The most affected software includes AMP for WP (1), Donorbox (1), Slim SEO (1), across 5 distinct plugins, themes and core versions in total.

All 5 disclosed issues have since received a vendor fix.

201820192020202120222023202420252026

Critical

High

Medium

Low

Global Rank

#857

of 3,878 researchers

Vulns

Critical0

High0

Medium5

Low0

Affected Assets

5plugins

Avg CVSS

6.0

Average score of vulnerabilities

Researcher Submissions

5 records


2026-09-11 00:00	Slim SEO – AI SEO Plugin, Lightweight, Fast & Automated <= 4.10.0 - Authenticated (Contributor+) Insecure Direct Object Reference Slim SEO <= 4.10.0	`CVE-2026-62113`	4.3 Medium	Sybre Waaijer	Yes
2022-09-19 00:00	Contact Form by WPForms <= 1.7.5.3 - Authenticated (Administrator+) Arbitrary File Access via Path Traversal WPForms <= 1.7.5.3	`N/A`	6.8 Medium	Sybre Waaijer	Yes
2019-12-19 00:00	Donorbox <= 7.1.1 - Authenticated Stored Cross-Site Scripting Donorbox < 7.1.2	`N/A`	6.4 Medium	Sybre Waaijer	Yes
2019-07-09 00:00	Yoast SEO <= 11.5 - Authenticated Stored Cross Site Scripting Yoast SEO <= 11.5	`CVE-2019-13478`	6.4 Medium	Sybre Waaijer	Yes
2018-10-20 00:00	AMP for WP <= 0.9.97.19 - Missing Authorization AMP for WP <= 0.9.97.19	`N/A`	6.3 Medium	Sybre Waaijer	Yes

Showing 1–5 of 5 reports