CVE-2023-2236

Local privilege escalation via duplicate file release

Published May 1, 2023 · Updated Mar 5, 2025

Use-after-free in Linux Kernel 5.19 through 6.0 allows local users to gain elevated privileges via io_uring file registration. The io_install_fixed_file error path calls fput after its callers also release the same file reference, underflowing the reference count and leaving a freed file object reachable. Low-privileged local access is required; successful exploitation crosses the kernel trust boundary and grants elevated privileges.

CVSS severity7.8
High
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Linux Kernel 5.19 through 6.0 allows local users to gain elevated privileges via io_uring file registration. The io_install_fixed_file error path calls fput after its callers also release the same file reference, underflowing the reference count and leaving a freed file object reachable. Low-privileged local access is required; successful exploitation crosses the kernel trust boundary and grants elevated privileges.

The record

CVE
CVE-2023-2236
Published
May 1, 2023
Updated
Mar 5, 2025
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-416, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 1, 2023CVE publishedPublication date reported by the CVE source.
  2. Mar 5, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.19 <6.1

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=5.19 <6.1

Published CVSS scores

7.8Google LLCCVSS: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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