CVE-2023-1998

Advisory lineage Upstream: 0 Downstream: 37
Modified
Published: 21 Apr 2023, 14:51
Last modified:13 Feb 2025, 16:39

Vulnerability Summary

Overall Risk (default)
medium
32/100
CVSS Score
5.6 MEDIUM
v3.1 (cve.org)
EPSS Score
0.11% LOW
0% probability +0.07%
KEV
Not listed
Ransomware
No reports
Public exploits
2 found
Dark Web
Not detected

Timeline

21 Apr 2023, 14:51
Published
Vulnerability first disclosed
13 Feb 2025, 16:39
Last Modified
Vulnerability information updated

Description

The Linux kernel allows userspace processes to enable mitigations by calling prctl with PR_SET_SPECULATION_CTRL which disables the speculation feature as well as by using seccomp. We had noticed that on VMs of at least one major cloud provider, the kernel still left the victim process exposed to attacks in some cases even after enabling the spectre-BTI mitigation with prctl. The same behavior can be observed on a bare-metal machine when forcing the mitigation to IBRS on boot command line. This happened because when plain IBRS was enabled (not enhanced IBRS), the kernel had some logic that determined that STIBP was not needed. The IBRS bit implicitly protects against cross-thread branch target injection. However, with legacy IBRS, the IBRS bit was cleared on returning to userspace, due to performance reasons, which disabled the implicit STIBP and left userspace threads vulnerable to cross-thread branch target injection against which STIBP protects.

CVSS Metrics

  • v3.1•MEDIUM•Score: 5.6CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N

EPSS Trends

Current EPSS score: 0.11%• Percentile: 30%

Techniques & Countermeasures

  • CWE-1303•Non-Transparent Sharing of Microarchitectural Resources

    Hardware structures shared across execution contexts (e.g., caches and branch predictors) can violate the expected architecture isolation between contexts.

  • CWE-203•Observable Discrepancy

    The product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor.

Affected Systems

  • debian•debian_linux

    10.0

  • linux•linux_kernel

    < 6.3

References (5)