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Lauritz

@lauritz-holtmann.de
342 followers 299 following 35 posts

IT-Security Researcher, Pentester and Bug Hunter. Passionate about 💻, 🤽‍♂️, ⚜️, 🎸 and ⚽ #meinVfL #Kaeferjaeger + H1 Ambassador 🏠 security.lauritz-holtmann.de

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Lauritz @lauritz-holtmann.de · 29/06/2026
leHACK 2026, c’était une vraie fête.🇫🇷 I had an awesome time in #Paris for this year's edition of @le-hack.bsky.social, "Brave New World". It was a great conference - my first time attending - with great talks, a mini LHE hosted by @yeswehack.bsky.social with Puma as the target, and meeting friends.
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Lauritz @lauritz-holtmann.de · 25/06/2026
I'll be around in #Paris at @le-hack.bsky.social over the next few days. Do not hesitate to say "hi" if you bump into me or ping me if you want to have a chat about #BugBounty -related things! :)
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Lauritz @lauritz-holtmann.de · 06/05/2026
Hacking Meetup "Friendly Edition" 🇳🇱 vs 🇩🇪 The @hacker0x01.bsky.social Club Netherlands and HackerOne Club Germany are teaming up for a cross-club bug bounty competition - inspired by the HackerOne Ambassador World Cup. #BugBounty #Meetup (1/3)
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Lauritz @lauritz-holtmann.de · 07/01/2026
Bug Bounty Meetup vol. 5 of the German @hacker0x01.bsky.social club will be held Feb 14th to Feb 22nd (remote). 👨‍💻 20 seats, swag, remote space for networking, a bug bounty target and lots of collaboration. RSVP now: h1.community/e/mbcd6v/
Screenshot taken from https://valdotr.github.io/medium-webinar/map.json by Vlado Romao.
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Lauritz @lauritz-holtmann.de · 23/12/2025
[Blog Post] Turning the List-Unsubscribe SMTP Header into an SSRF/XSS Gadget security.lauritz-holtmann.de/post/xss-ssr... Once again, ancient RFCs and overlooked security hot spots in specifications turned out to be worthwhile for security research. Read the spec!
security.lauritz-holtmann.de
Turning List-Unsubscribe into an SSRF/XSS Gadget
The List-Unsubscribe SMTP header is standardized but often overlooked during security assessments. It allows email clients to provide an easy way for end-users to unsubscribe from mailing lists. This ...
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Lauritz @lauritz-holtmann.de · 06/10/2025
Recap of our @hacker0x01.bsky.social Hacking Meetup in September 👀 Leaderboard (still in progress): leaderboards.hackerone.live/germany-meet... 👉 h1.community/e/mbkdm3/ #BugBounty #Meetup #HackerOne
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Reposted by Lauritz
Oli (C..1..P.H.Y) @munz4u.de · 26/06/2025
I reported a single, highly critical vulnerability that earned the top payout of the event. 💥🐞 Big thanks to @exness6.bsky.social for putting together such a great virtual meetup, and a special shoutout to @lauritz-holtmann.de! Everything was incredibly well organized! 🙌
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Lauritz @lauritz-holtmann.de · 26/06/2025
Hacking Meetup vol. 3 of the German @hacker0x01.bsky.social Club - supported by @exnessofficial.bsky.social - was a blast! 💥 We x6 the overall bounties of our previous meetup and scored over 94,000$ overall bounties. 🤯 Additionally, H1 swag is on the way to all attendees and will arrive soon. 🤞
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Lauritz @lauritz-holtmann.de · 27/03/2025
Our @hacker0x01.bsky.social meetup (vol.2) last month was a blast! 🔥 Almost 40 signups, ~25 active remote attendees and 12 attendees from all over Germany who travelled to #Bochum and hacked together in person on Grab's assets. 🤯 #BugBounty #Meetup
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Lauritz @lauritz-holtmann.de · 04/02/2025
🧑‍💻 #BugBounty Meetup Vol. 2 of the German @hacker0x01.bsky.social Club x Grab The event is organised like a Mini-LHE: 📅 15.02. - 21.02.25 Remote Hacking 📅 22.02.25 In-Person Day 📍#Bochum (Work Inn Bochum-FiftyOne) ‼️ Signup Deadline: Wednesday, Feb 12th. 👉 h1.community/e/mgswsg/
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Lauritz @lauritz-holtmann.de · 06/01/2025
The new year starts with a bang: #BugBounty Meetup Vol. 2 of the German @hacker0x01.bsky.social Club will take place on February 22nd in #Bochum, Germany! 🧑‍💻 We will organize the event like a Mini-LHE: Like last year, there will be again a collaborating H1 program and a leaderboard. (1/3)
LHE Leaderboard of the last H1 Meetup in Bochum
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Lauritz @lauritz-holtmann.de · 30/12/2024
#38c3 was 🚀
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Lauritz @lauritz-holtmann.de · 27/12/2024
Just landed at #38c3 🤩 Ping me here or via ☎️5876 if you want have a chat, talk about things like #BugBounty or just want to have a Tschunk together. :) I also have a handful of #H1 stickers with me to spread. 😏
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Lauritz @lauritz-holtmann.de · 27/12/2024
🔜🚀 #38c3
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Lauritz @lauritz-holtmann.de · 18/12/2024
Blog: #Android App Links Allowed Hijacking Arbitrary #SSO Flows 👉 security.lauritz-holtmann.de/post/sso-and... Discover how twitter.com/_kun_19 and I uncovered a severe issue allowing hijack of SSO flows on Android… only to find we were years late to the party. #BugBounty #Security #FuckUp
security.lauritz-holtmann.de
Android App Links autoVerify=false Allowed Hijacking Authentication Flows
Research is a constant process of failure and iteration. However, in most cases, you only see the one-in-a-thousand (successful) attempt. To normalize f*ck ups, and because I believe the behavior we i...
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Lauritz @lauritz-holtmann.de · 23/11/2024
Got my #38c3 ticket, see you in Hamburg 🚀
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Lauritz @lauritz-holtmann.de · 21/11/2024
The "Dead Domain Discovery" Extension is now available from Chrome Web Store: 👉 chromewebstore.google.com/detail/opfeo... Keep in mind that the extension needs broad permissions to work. I'd recommend to only install it to your "research browser". Github: github.com/lauritzh/dea...
chromewebstore.google.com
Dead Domain Discovery - Chrome Web Store
Scans the page for external iFrames, Scripts, and Styles, logs them to the console, and checks if their domains are resolvable.
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Lauritz @lauritz-holtmann.de · 15/11/2024
The Flickr ATO using AWS Cognito recently turned "3" and it is still my favorite bug bounty story 😅 Check out the blog post in case you missed it: security.lauritz-holtmann.de/advisories/f... H1 disclosure: hackerone.com/reports/1342...
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Lauritz @lauritz-holtmann.de · 30/11/2023
#BurpSuite #Bambda to detect Blind SSRF via OpenID Connect "request_uri" using out-of-bound detection (e.g. Collaborator). The vulnerable URL is b64-encoded and included within the canary URL. 👉 gist.github.com/lauritzh/7b3... 📚 security.lauritz-holtmann.de/post/sso-sec...
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Lauritz @lauritz-holtmann.de · 29/11/2023
Got my ticket for #37c3 - see you there! 🚀
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