CVE-2021-28375

Local privilege escalation via reserved FastRPC handle

Published Mar 15, 2021 · Updated Aug 3, 2024

Improper privilege management in Linux kernel 5.11.6 and earlier allows local users to gain elevated privileges through FastRPC. The fastrpc_internal_invoke function accepts FASTRPC_INIT_HANDLE from user-space calls and forwards the reserved kernel RPC handle, directly attaching an application to the remote subsystem. A local user must be able to access the FastRPC device; the resulting kernel RPC path crosses the intended user-to-kernel privilege boundary.

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

What happened

Improper privilege management in Linux kernel 5.11.6 and earlier allows local users to gain elevated privileges through FastRPC. The fastrpc_internal_invoke function accepts FASTRPC_INIT_HANDLE from user-space calls and forwards the reserved kernel RPC handle, directly attaching an application to the remote subsystem. A local user must be able to access the FastRPC device; the resulting kernel RPC path crosses the intended user-to-kernel privilege boundary.

The record

CVE
CVE-2021-28375
Published
Mar 15, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-269, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 15, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.2NIST NVDAV:L/AC:L/Au:N/C:C/I:C/A:C
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-269Improper Privilege Management
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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