CVE-2021-47358

Kernel memory corruption via premature tty release

Published May 21, 2024 · Updated Aug 5, 2026

Use-after-free in the Greybus UART driver in Linux 4.9 and later affected branches allows local users to corrupt kernel memory after disconnect. The removal path frees gb_tty state without waiting for the tty port's final reference, leaving an open descriptor attached to released storage. A local user must keep /dev/ttyGB* open across a Greybus UART disconnect and reuse the descriptor, which can crash the system or execute code in kernel context.

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 Greybus UART driver in Linux 4.9 and later affected branches allows local users to corrupt kernel memory after disconnect. The removal path frees gb_tty state without waiting for the tty port's final reference, leaving an open descriptor attached to released storage. A local user must keep /dev/ttyGB* open across a Greybus UART disconnect and reuse the descriptor, which can crash the system or execute code in kernel context.

The record

CVE
CVE-2021-47358
Published
May 21, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 21, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2026Record 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=4.9
  2. Affected versionversion=a18e15175708d39abbe9746ddc3479466b7800c3 <4dc56951a8d9d61d364d346c61a5f1d70b4f5e14
  3. Affected versionversion=a18e15175708d39abbe9746ddc3479466b7800c3 <64062fcaca8872f063ec9da011e7bf30470be33f
  4. Affected versionversion=a18e15175708d39abbe9746ddc3479466b7800c3 <92b67aaafb7c449db9f0c3dcabc0ff967cb3a42d
  5. Affected versionversion=a18e15175708d39abbe9746ddc3479466b7800c3 <92dc0b1f46e12cfabd28d709bb34f7a39431b44f
  6. Affected versionversion=a18e15175708d39abbe9746ddc3479466b7800c3 <9872ff6fdce8b229f01993b611b5d1719cb70ff1
  7. Affected versionversion=a18e15175708d39abbe9746ddc3479466b7800c3 <a5cfd51f6348e8fd7531461366946039c29c7e69
  8. Affected versionversion=a18e15175708d39abbe9746ddc3479466b7800c3 <b9e697e60ce9890e9258a73eb061288e7d68e5e6

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.9; version=a18e15175708d39abbe9746ddc3479466b7800c3 <4dc56951a8d9d61d364d346c61a5f1d70b4f5e14; version=a18e15175708d39abbe9746ddc3479466b7800c3 <64062fcaca8872f063ec9da011e7bf30470be33f; version=a18e15175708d39abbe9746ddc3479466b7800c3 <92b67aaafb7c449db9f0c3dcabc0ff967cb3a42d; version=a18e15175708d39abbe9746ddc3479466b7800c3 <92dc0b1f46e12cfabd28d709bb34f7a39431b44f; version=a18e15175708d39abbe9746ddc3479466b7800c3 <9872ff6fdce8b229f01993b611b5d1719cb70ff1; version=a18e15175708d39abbe9746ddc3479466b7800c3 <a5cfd51f6348e8fd7531461366946039c29c7e69; version=a18e15175708d39abbe9746ddc3479466b7800c3 <b9e697e60ce9890e9258a73eb061288e7d68e5e6

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.8Linux kernelCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
4.7Amazon LinuxCVSS:3.1/AV:L/AC:H/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 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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