CVE-2021-1048Known exploitation

Local privilege escalation via stale epoll file reference

Published Dec 15, 2021 · Updated Oct 21, 2025

Use-after-free in the Android kernel allows local users to escalate privileges by exercising epoll without user interaction. ep_loop_check_proc calls get_file on an epoll file already committed to destruction, retaining an invalid reference during reverse-path checking. Code execution with low privileges is required to reach the kernel path, and successful memory corruption grants higher local privileges.

CVSS severity7.8
High
EPSS probability1.04%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in the Android kernel allows local users to escalate privileges by exercising epoll without user interaction. ep_loop_check_proc calls get_file on an epoll file already committed to destruction, retaining an invalid reference during reverse-path checking. Code execution with low privileges is required to reach the kernel path, and successful memory corruption grants higher local privileges.

The record

CVE
CVE-2021-1048
Published
Dec 15, 2021
Updated
Oct 21, 2025
Vendor
Google Cloud
Product
Android
Classifications
CWE-416, T1404
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 15, 2021CVE publishedPublication date reported by the CVE source.
  2. May 23, 2022Exploitation reportedCISA Known Exploited Vulnerabilities listing
  3. Oct 21, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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  1. Affected versionversion=Android kernel

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Google Cloud · Androidversion=Android kernel

Published CVSS scores

7.8CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationReported
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1404Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

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Reported exploitation

Technologies

Your stack

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Your stack

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