CVE-2021-1048

CVE-2021-1048 is a use-after-free (CWE-416) in ep_loop_check_proc of eventpoll.c — the Android kernel's epoll event-notification code — that can corrupt kernel memory. A local attacker (e.g., a malicious app with no special permissions) can trigger the flaw, and no user interaction is required, yielding local escalation of privilege to kernel level. Any Android device running an unpatched Android kernel is affected. The flaw is being actively exploited: it is in CISA's Known Exploited Vulnerabilities Catalog (added 2022-05-23) and reporting indicates Google fixed it as a zero-day used in targeted attacks, with coverage tying Android kernel zero-days to Cytrox/Intellexa Predator spyware campaigns. EPSS currently puts the 30-day exploitation probability at ~1.0%, but the KEV listing and in-the-wild targeting make patching urgent.

What to do: Apply updates per vendor instructions (CISA KEV required action): install the latest Android security/kernel updates from Google or your device OEM — Google's advisories indicate the complete fix shipped in the February 2022 Android security bulletin (2022-02-05 patch level), following the initial January 2022 fix. Fleet administrators should verify devices' security patch levels and prioritize high-value/targeted users, since observed exploitation has been targeted (spyware-linked) rather than mass-scale. No public PoC is known and ransomware use is unknown, but defenders should hunt for signs of local privilege escalation on unpatched fleets.