CVE-2021-47026

Kernel memory corruption via RTRS session-removal race

Published Feb 28, 2024 · Updated May 11, 2026

Use-after-free in the Linux kernel RTRS client allows local users to corrupt kernel memory during concurrent session removal. rtrs_clt_remove_path_from_sysfs frees sess->stats before removing the session from the active list, so rtrs_clt_request or get_next_path_min_inflight can update the freed object. Reachability requires an active RTRS client session and a race between path removal and I/O or path selection; the documented consequence is use-after-free access to session statistics.

CVSS severity7.8
High
EPSS probability0.24%
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 RTRS client allows local users to corrupt kernel memory during concurrent session removal. rtrs_clt_remove_path_from_sysfs frees sess->stats before removing the session from the active list, so rtrs_clt_request or get_next_path_min_inflight can update the freed object. Reachability requires an active RTRS client session and a race between path removal and I/O or path selection; the documented consequence is use-after-free access to session statistics.

The record

CVE
CVE-2021-47026
Published
Feb 28, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 28, 2024CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record 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=5.8
  2. Affected versionversion=6a98d71daea186247005099758af549e6afdd244 <676171f9405dcaa45a33d18241c32f387dbaae39
  3. Affected versionversion=6a98d71daea186247005099758af549e6afdd244 <7f4a8592ff29f19c5a2ca549d0973821319afaad
  4. Affected versionversion=6a98d71daea186247005099758af549e6afdd244 <b64415c6b3476cf9fa4d0aea3807065b8403a937
  5. Affected versionversion=6a98d71daea186247005099758af549e6afdd244 <d3cca8067d43dfee4a3535c645b55f618708dccb

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.8; version=6a98d71daea186247005099758af549e6afdd244 <676171f9405dcaa45a33d18241c32f387dbaae39; version=6a98d71daea186247005099758af549e6afdd244 <7f4a8592ff29f19c5a2ca549d0973821319afaad; version=6a98d71daea186247005099758af549e6afdd244 <b64415c6b3476cf9fa4d0aea3807065b8403a937; version=6a98d71daea186247005099758af549e6afdd244 <d3cca8067d43dfee4a3535c645b55f618708dccb

Published CVSS scores

7.8NIST NVDCVSS: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 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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