CVE-2023-1998Public exploit

Cross-thread data disclosure via disabled STIBP

Published Apr 21, 2023 · Updated Feb 13, 2025

Information disclosure in Linux Kernel before 6.3 allows local users to read victim-process data via cross-thread branch target injection. In arch/x86/kernel/cpu/bugs.c, spectre_v2_user_select_mitigation() treats legacy IBRS like enhanced IBRS and returns without enabling STIBP, although legacy IBRS clears its protection on return to userspace. Exploitation requires low-privilege code on a sibling SMT thread of the same physical core while the victim relies on prctl or seccomp protection, exposing victim-process data without reported integrity or availability effects.

CVSS severity5.6
Medium
EPSS probability1.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Linux Kernel before 6.3 allows local users to read victim-process data via cross-thread branch target injection. In arch/x86/kernel/cpu/bugs.c, spectre_v2_user_select_mitigation() treats legacy IBRS like enhanced IBRS and returns without enabling STIBP, although legacy IBRS clears its protection on return to userspace. Exploitation requires low-privilege code on a sibling SMT thread of the same physical core while the victim relies on prctl or seccomp protection, exposing victim-process data without reported integrity or availability effects.

The record

CVE
CVE-2023-1998
Published
Apr 21, 2023
Updated
Feb 13, 2025
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-203, CWE-1303, CAPEC-663
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 21, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 2025Record 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=0 <6.3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=0 <6.3

Published CVSS scores

5.6Google Inc.CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N

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 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 exploitPublished

Weakness, pattern, technique

CWE-203Observable Discrepancy
CWE-1303Non-Transparent Sharing of Microarchitectural Resources
CAPEC-663Exploitation of Transient Instruction Execution

Public exploit references

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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