Simon Willison’s Weblog

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5 items tagged “samesite”

2024

In 2021 we [the Mozilla engineering team] found “samesite=lax by default” isn’t shippable without what you call the “two minute twist” - you risk breaking a lot of websites. If you have that kind of two-minute exception, a lot of exploits that were supposed to be prevented remain possible.

When we tried rolling it out, we had to deal with a lot of broken websites: Debugging cookie behavior in website backends is nontrivial from a browser.

Firefox also had a prototype of what I believe is a better protection (including additional privacy benefits) already underway (called total cookie protection).

Given all of this, we paused samesite lax by default development in favor of this.

Frederik Braun

# 26th August 2024, 8:26 pm / mozilla, browsers, security, cors, cookies, privacy, firefox, samesite

2021

Exploring the SameSite cookie attribute for preventing CSRF

Visit Exploring the SameSite cookie attribute for preventing CSRF

In reading Yan Zhu’s excellent write-up of the JSON CSRF vulnerability she found in OkCupid one thing puzzled me: I was under the impression that browsers these days default to treating cookies as SameSite=Lax, so I would expect attacks like the one Yan described not to work in modern browsers.

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Datasette 0.58: The annotated release notes

I released Datasette 0.58 last night, with new plugin hooks, Unix domain socket support, a major faceting performance fix and a few other improvements. Here are the annotated release notes.

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2020

2020 Web Milestones (via) A lot of stuff is happening in 2020! Mike Sherov rounds it up—highlights include the release of Chromium Edge (Microsoft’s Chrome-powered browser for Windows 7+), Web Components supported in every major browser, Deno 1.x, SameSite Cookies turned on by default (which should dramatically reduce CSRF exposure) and Python 2 and Flash EOLs.

# 24th January 2020, 4:43 am / chrome, csrf, flash, ie, javascript, python, web, deno, samesite

Come version 80, any cookie without a SameSite attribute will be treated as "Lax" by Chrome. This is really important to understand because put simply, it'll very likely break a bunch of stuff. [...] The fix is easy, all it needs is for everyone responsible for maintaining any system that uses cookies that might be passed from an external origin to understand what's going on. Can't be that hard, right? Hello? Oh...

Troy Hunt

# 3rd January 2020, 4:22 pm / csrf, cookies, chrome, samesite