cm0002It's janky AF
Sarah Valentine (she/her)I don’t know what “image proxying” is. Can someone give me the q&d?
WiddershinsIs it the "?format= " at the end of a url that usually turns a quick download of a .jpg or .gif into a .webp or .webm download?
I fuckin hate webp format. Pointless format given the use case coverage between jpg and png.
I usually change the url to “.jpeg?format=jpeg” just in case that formatting takes any extra computing on their end. They want to use a boondoggle I’m gonna use the boondoggle.
Yep. And most damning, a lot of my image viewing or editing apps don’t like the webp format.
It’s a feature of Lemmy where your instance will proxy image links for you, it can be useful in some cases to do things like bypass regional censorships (If you can access your home instance from your country, but not instance lemmy.example.com your home instance can proxy the image from lemmy.example.com so you can still see it (text is handled by federation already, so no proxy required for just text)) or to cache images in case an instance goes down
But it seems to be poorly implemented where it’s end user experience is a pain at best, and the more aggressive it’s set the more annoying it is.
Take for example this instance I’m currently on, infosec.pub, they seem to have it set to aggressively replace all image links including in comments no matter what.
So now my attempt to reply to this comment infosec.pub/comment/20590443 is utterly broken because the image service just doesn’t like it despite me just wanting to link to the off-site gif link manually typing the markdown instead.
This is what that gif looks like proxied:
I was wondering why your reply shows up empty on my instance.
Neither of those links display an image for me. One shows a tiny empty box in your comment and the other lands me on a weird little error page about “msg too wide”
Yeah, because the proxy has decided it doesn’t like it
This is what I actually wanted to link to/embed
i.ibb.co/8gHKNsT1/michael-scott-why.gif
Well actually I originally tried with a direct tenor link
But it didn’t like that either
Tenor in particular is shitty like that too. If I directly link to a tenor gif on discord, people have to click the link and open a webpage to view the gif. To embed it in discord I have to save it and upload it.
{
"code": "validate-width",
"msg": "Too wide"
}
stripped the headers, your image didn’t make it through the infosec.pub proxy.
X-Firefox-Spdy: h2
access-control-expose-headers: vary, date, content-length, content-encoding, content-type
cache-control: public, max-age=60
content-encoding: br
content-type: application/json
date: Fri, 27 Feb 2026 02:10:57 GMT
server: nginx
vary: accept-encoding, Origin, Access-Control-Request-Method, Access-Control-Request-Headers
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Encoding: gzip, deflate, br, zstd
Accept-Language: en-US,en;q=0.5
Connection: keep-alive
DNT: 1
Host: infosec.pub
Priority: u=0, i
Referer: https://piefed.social/
Sec-Fetch-Dest: document
Sec-Fetch-Mode: navigate
Sec-Fetch-Site: cross-site
Sec-Fetch-User: ?1
Sec-GPC: 1
TE: trailers
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:140.0) Gecko/20100101 Firefox/140.0
MikeThe proxy link returns a funny error; “too wide.”
It’s a gif of OP’s mom
A good thing about proxying is that it prevents auto-loading of resources from potentially malicious domains. For instance, I could make an image comment containing an image link to a server I control. When you reply to my comment, since you clearly have seen my comment, I can now look at my server logs and see the IP addresses of everyone who viewed my image. I now know that your IP address is in that list.
Exactly this.
SorteKaninI’ve heard this security concern before, but I’m a bit confused about the real attack vector here. I mean let’s say you do this - you post an image to some random Lemmy instance and behind the scenes, you gather all the IPs which fetch the image. What malicious thing could you do with that? Genuinely curious.
MrNobody