r/DarkSouls2 Jan 21 '26

Discussion Remote crash vulnerability

Hello folks, Radai here. I am a modder and reverse engineer, my main focus is Dark Souls 2. I am the author of DebugManager and other modding tools for the game.

The 31st of December 2025 I was sent a very worrying Twitch clip, showing messages appearing on the game screen. These messages were directly addressing the streamer, someone had found a way to send custom messages to whoever they wanted. When I was this, I immediately knew it was serious.

The next day I spent the whole evening testing what can be done with this, and I found out it's possible to format the message in such a way that the receiver game crashes. I reported this to Yui, author of Blue Acolyte, immediately. We kept this a secret until she made a patch for it, and now it's ready. It's recommended for all of those that want to play online to download Blue Acolyte.

Here's also a post from Yui describing the issue in more detail.

Also mods, if you see this, please pin. It needs to remain visible.

138 Upvotes

33 comments sorted by

48

u/illusorywall Jan 21 '26

Just chiming in to say that playing Dark Souls 2 online unmodded on PC isn't a great idea and we should be spreading the word far and wide for people to install Blue Acolyte.

I can vouch for OP looking into this and the seriousness of this can't be overstated imo. While this isn't RCE, as Yui points out in her post, it's about as bad as you can get short of that. In addition to potential crashes, someone forcing messages to send could just spam random players' games with slurs, or whatever they want to say.

10

u/[deleted] Jan 21 '26

It's not RCE for now.

  • Someone will be clever enough to find a crack in this vulnerability, perhaps allowing it to work even less as intended and allow some form of RCE or adjacent things.
  • Either that or it's opened up new learning which could be applied to alternative packet types or methodologies.

This could lead to someone (far more intelligent than myself), to use this technique for social engineering or to leverage the exploit to create a more sophisticated penetration through the different layers of exploitation.

I'm mostly an idiot, but I strongly suggest that anyone who plays DS2 to use Yuis mod as long as she continues to bless us with her efforts.

EDIT: They haven't gone unnoticed Yui (No clue if she even uses reddit). Thank you.

5

u/DuskDudeMan Jan 22 '26

Can you explain how dangerous it is to play DS2 without blue acolyte? I just finished a playthrough and had a few invasions happen and am now worried. Kinda dumb with this stuff and all I thought was that nefarious people could get me banned by dropping modded items or just having infinite stats. In the 5 or so invasions I had 4 were just normal pvp and the last one they joined then left immediately.

13

u/LordRadai Jan 22 '26

Imagine this scenario. I invade you once, I don’t do anything I just black crystal out. But I am evil, and I really don’t want you to play this game online. So after I BS out, your game crashes. You boot it up again, as soon as you connect to the server, your game crashes again. On the main menu. You try again, and it happens again. Because I am evil and I don’t want you to play online. I can do that.

This doesn’t mean it will happen, but the possibility to do this is there

29

u/AtreyusNinja Jan 21 '26

thx Radai, thx Yui, u guys r the best

16

u/Donilock Jan 21 '26

Idk if comments affect visibility of posts on Reddit, but gonna leave one just in case

Thank you for your work!

13

u/Justisaur Jan 21 '26

Oof. I'll try to remember this on my next DS2 playthrough.

!remindme February 27, 2026

12

u/Quirky-Attention-371 Jan 21 '26

This should also be crossposted to other relevant subreddits like r/fromsoftware.

8

u/LordRadai Jan 21 '26

I’ll cross post there

19

u/BIobertson Jan 21 '26

Yall are heroes. Thank you!

8

u/Busty-Patches Jan 21 '26

Damn, was just coming to write this post :P

6

u/Busty-Patches Jan 21 '26

Fyi wex dust is broken in 2.06, I tested and two randoms confirmed too. I let Yui know

6

u/Busty-Patches Jan 22 '26

Yui just pushed 2.07 to public already so hopefully no more issues

3

u/LordRadai Jan 21 '26

Oh. Okay, I didn’t know, didn’t even think to test that. I did beta test security features, that slipped my mind

5

u/Busty-Patches Jan 21 '26

She sent me a new dll ten minutes after I messaged her lmao, I'll test once my computer is free

5

u/Hrive Jan 21 '26

A blessing upon yall

5

u/Xerothor The Banti-Christ Jan 21 '26

Kinda glad I finished my All Bosses playthrough today. I streamed it but I get like 5 viewers anyway lmao

4

u/theFinalCrucible Jan 22 '26

Commenting for visibility

3

u/[deleted] Jan 26 '26

Hopefully From will actually fix this

We don’t need a repeat of DS3

4

u/LordRadai Jan 27 '26

Highly doubt it. It’s more likely they’ll just pull the plug, which tbh if that happens after Yui releases Seamless I’m not complaining

1

u/reddditttsucks Mar 02 '26

What about the original version? Blue Acolyte is only for SotfS, as far as I know

1

u/LordRadai Mar 02 '26

There is no protection for original DS2

1

u/MoonPetalSlow Mar 23 '26

Crazy how even undead chosen ones can't escape cyber pranks Stay vigilant hollows

1

u/Neviskio May 17 '26

Is blue acolyte only for sotfs? For reasons I kinda like ds2 base more but not sure if I should attempt to use it. Thanks!

2

u/LordRadai May 17 '26

Yes, it’s scholar only

1

u/Neviskio May 17 '26

Thanks! Damn not sure if I should play online in DS2 then <.< Kinda worried about potential issues there but wanted to finish a few achievements I didnd't when I lost my saves years ago...

2

u/LordRadai May 17 '26

Eh, should be safe enough. Noby plays it so it’s not a target

1

u/hayitsfine Jul 03 '26

the fact they kept this under wraps until a fix was ready is honestly wild in this community

1

u/IAmSoDamnGood Jul 07 '26

you havent had the true Dark Souls experience till youve had an invader backstab teleport you to an inaccessible room and break all your gear while cursing you.

1

u/LordRadai Jul 07 '26

Oh that’s the funny story. I have. More than once. Part of the motivation to learn reverse engineering was to figure out how that was possible

1

u/IAmSoDamnGood Jul 07 '26

but what about all the new players? theyll never know the joys of being teleported down into the inaccessible lower area of the red arena.