CVE-2021-47401

Kernel stack disclosure via dangling tty name

Published May 21, 2024 · Updated Aug 5, 2026

Information disclosure in the ipoctal tty driver in Linux 3.5 and later before branch-specific fixes allows local users to read kernel stack data. The driver registers a name pointer to a stack-local tty_name buffer, then later prints the dangling C string through /proc/tty/drivers after that storage is reused. Exploitation requires the IP-OCTAL driver to probe and an unprivileged local user to read the proc entry; disclosure can expose kernel pointers or trigger a kernel oops.

CVSS severity7.1
High
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Information disclosure in the ipoctal tty driver in Linux 3.5 and later before branch-specific fixes allows local users to read kernel stack data. The driver registers a name pointer to a stack-local tty_name buffer, then later prints the dangling C string through /proc/tty/drivers after that storage is reused. Exploitation requires the IP-OCTAL driver to probe and an unprivileged local user to read the proc entry; disclosure can expose kernel pointers or trigger a kernel oops.

The record

CVE
CVE-2021-47401
Published
May 21, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
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=3.5
  2. Affected versionversion=ba4dc61fe8c545a5d6a68b63616776556b771f51 <0a9c36a2e06a249acbed64e8e0b84637c2ad7575
  3. Affected versionversion=ba4dc61fe8c545a5d6a68b63616776556b771f51 <2725925982dc96a78069cd118ea3d66759bfdad7
  4. Affected versionversion=ba4dc61fe8c545a5d6a68b63616776556b771f51 <5f6a309a699675680df15d9b6d389114515b4426
  5. Affected versionversion=ba4dc61fe8c545a5d6a68b63616776556b771f51 <741ea2670e021350e54f491106bdaa22dc50e6a0
  6. Affected versionversion=ba4dc61fe8c545a5d6a68b63616776556b771f51 <829f13d6079cf7a2465522f39acb43033e9b320d
  7. Affected versionversion=ba4dc61fe8c545a5d6a68b63616776556b771f51 <8657158a3b68c85234e6da3d8eae33d6183588b7
  8. Affected versionversion=ba4dc61fe8c545a5d6a68b63616776556b771f51 <a89936cce87d60766a75732a9e7e25c51164f47c
  9. Affected versionversion=ba4dc61fe8c545a5d6a68b63616776556b771f51 <acb96e782bad427ca4bb1bd94af660acd1462380

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.5; version=ba4dc61fe8c545a5d6a68b63616776556b771f51 <0a9c36a2e06a249acbed64e8e0b84637c2ad7575; version=ba4dc61fe8c545a5d6a68b63616776556b771f51 <2725925982dc96a78069cd118ea3d66759bfdad7; version=ba4dc61fe8c545a5d6a68b63616776556b771f51 <5f6a309a699675680df15d9b6d389114515b4426; version=ba4dc61fe8c545a5d6a68b63616776556b771f51 <741ea2670e021350e54f491106bdaa22dc50e6a0; version=ba4dc61fe8c545a5d6a68b63616776556b771f51 <829f13d6079cf7a2465522f39acb43033e9b320d; version=ba4dc61fe8c545a5d6a68b63616776556b771f51 <8657158a3b68c85234e6da3d8eae33d6183588b7; version=ba4dc61fe8c545a5d6a68b63616776556b771f51 <a89936cce87d60766a75732a9e7e25c51164f47c; version=ba4dc61fe8c545a5d6a68b63616776556b771f51 <acb96e782bad427ca4bb1bd94af660acd1462380

Published CVSS scores

7.1Linux CNACVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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

No sourced classifications are available.

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo