Copy Fail (CVE-2026-31431): Fleet Mitigation and Outcome
🔒 Cloudflare assessed and mitigated the Linux local privilege escalation named Copy Fail (CVE-2026-31431) following public disclosure on 2026-04-29. Our behavioral detections flagged the exploit chain within minutes during validation, and threat hunting across a 48-hour window found no evidence of compromise. We deployed an eBPF LSM allow-list (bpf-lsm) to block AF_ALG binds for non-allow-listed binaries, built and staged patched LTS kernels, and completed fleet protection via controlled reboots with no customer impact.
