Copy Fail: 732 Bytes to Root on Every Major Linux Distribution

AI for Security Vulnerability ResearchCopy Fail: 732 Bytes to Root on Every Major Linux Distribution.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.Apr 29, 2026ContentsWhat Makes Copy Fail DifferentThe Root Cause: Page Cache Pages in the Writable ScatterlistThe Trigger: authencesn's Scratch WriteHow This HappenedThe ExploitThe DemoThe FixRemediationCoordinated Disclosure TimelineHow We Found ItCopy Fail: 732 Bytes to Root on Every Major Linux Distribution.Xint Code Research TeamCopy Fail (CVE-2026-31431) is a logic bug in the Linux kernel's authencesn cryptographic template.

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