Post · bonfire.cafe

Patch your Linux boxes!

Copy.Fail is a trivially exploitable logic bug in Linux, reachable on all major distros released in the last 9 years. A small, portable python script gets root on all platforms.

Found by the teams at @theori_io and Xint
More details below
https://xint.io/blog/copy-fail-linux-distributions

Copy Fail: 732 Bytes to Root on Every Major Linux Distributions - Xint

Xint Code disclosed CVE-2026-31431, an authencesn scratch-write bug chaining AF_ALG + splice() into a 4-byte page cache write. A 732-byte PoC gets root on Ubuntu, Amazon Linux, RHEL, SUSE. | AI for Security, Vulnerability Research

Luc

@luc@chaos.social · 19 hours ago

@xint what do you mean "patch"? I like root! Though the device I was hoping for predates this bug so it's sadly safe :(

Xint

@xint@infosec.exchange · 18 hours ago

@luc you can find patch instructions here: https://copy.fail/#mitigation