CVE-2021-46928

Misleading trap diagnostics via stale instruction register

Published Feb 27, 2024 · Updated May 11, 2026

Improper exception handling in affected PA-RISC Linux kernels allows local users to produce misleading instruction-trap diagnostics. On trap 7, the CPU does not fetch the non-executable instruction or refresh cr19, but arch/parisc/kernel/traps.c reports the register's stale value. The flaw requires a PA-RISC system and local code that attempts execution from a non-executable memory region; it alters diagnostic output rather than granting data access or code execution.

CVSS severity5.5
Medium
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper exception handling in affected PA-RISC Linux kernels allows local users to produce misleading instruction-trap diagnostics. On trap 7, the CPU does not fetch the non-executable instruction or refresh cr19, but arch/parisc/kernel/traps.c reports the register's stale value. The flaw requires a PA-RISC system and local code that attempts execution from a non-executable memory region; it alters diagnostic output rather than granting data access or code execution.

The record

CVE
CVE-2021-46928
Published
Feb 27, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-755
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 27, 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=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <484730e5862f6b872dca13840bed40fd7c60fa26
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d01e9ce1af6116f812491d3d3873d204f10ae0b8
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e96373f0a5f484bc1e193f9951dcb3adf24bf3f7
  4. Affected versionversion=2.6.12

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <484730e5862f6b872dca13840bed40fd7c60fa26; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d01e9ce1af6116f812491d3d3873d204f10ae0b8; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e96373f0a5f484bc1e193f9951dcb3adf24bf3f7; version=2.6.12

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 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-755Improper Handling of Exceptional Conditions

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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