CVE-2023-53557

Kernel compromise via fprobe rethook use-after-free

Published Oct 4, 2025 · Updated Oct 4, 2025

Use-after-free in the Linux kernel fprobe subsystem allows local users with delegated tracing capabilities to compromise the kernel. unregister_fprobe frees fp->rethook before unregistering its ftrace operations, allowing callbacks still executing on another CPU to dereference freed memory. Reachability requires local bpf() access with CAP_BPF and CAP_PERFMON; successful exploitation can crash the system or corrupt kernel control flow.

CVSS severity5.5
Medium
EPSS probability0.15%
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 the Linux kernel fprobe subsystem allows local users with delegated tracing capabilities to compromise the kernel. unregister_fprobe frees fp->rethook before unregistering its ftrace operations, allowing callbacks still executing on another CPU to dereference freed memory. Reachability requires local bpf() access with CAP_BPF and CAP_PERFMON; successful exploitation can crash the system or corrupt kernel control flow.

The record

CVE
CVE-2023-53557
Published
Oct 4, 2025
Updated
Oct 4, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 4, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 4, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=5.18
  2. Affected versionversion=5b0ab78998e32564a011b14c4c7f9c81e2d42b9d <03d63255a5783243c110aec5e6ae2f1475c3be76
  3. Affected versionversion=5b0ab78998e32564a011b14c4c7f9c81e2d42b9d <5f81018753dfd4989e33ece1f0cb6b8aae498b82
  4. Affected versionversion=5b0ab78998e32564a011b14c4c7f9c81e2d42b9d <ce3ec57faff559ccae1e0150c1f077eb2df648a4

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.18; version=5b0ab78998e32564a011b14c4c7f9c81e2d42b9d <03d63255a5783243c110aec5e6ae2f1475c3be76; version=5b0ab78998e32564a011b14c4c7f9c81e2d42b9d <5f81018753dfd4989e33ece1f0cb6b8aae498b82; version=5b0ab78998e32564a011b14c4c7f9c81e2d42b9d <ce3ec57faff559ccae1e0150c1f077eb2df648a4

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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

T1499Endpoint Denial of Service

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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