CVE-2023-1998

Spectre v2 SMT mitigations problem in Linux kernel

MEDIUM 5.6

At a glance

Source
NVD
EPSS
EPSS 1.38 % · percentile 72 ()
State
PUBLISHED
Published
Updated
Assigner
Google
NVD status
Modified

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.

Weaknesses (CWE)

References

Scores

VersionScoreVectorScored by
CVSS 3.1MEDIUM 5.6CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:NGoogle
CVSS 3.1MEDIUM 5.6CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:NNVD · cve-coordination@google.com (Secondary)
CVSS 3.1MEDIUM 5.6CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:NNVD · nvd@nist.gov (Primary)

European references

CERT-FR advisories

Affected configurations (NVD CPE)

Affected products

ProductVersions
Linux · Linux Kernelaffected 0 < 6.3

Sources

SourceLicence
CVE List (CVEProject cvelistV5)CVE Program Terms of Use
EPSS (FIRST.org)FIRST — attribution requested
ENISA EUVDENISA — reproduction authorised, source acknowledged
CERT-FR (ANSSI)Licence Ouverte / Etalab 2.0
NVD (NIST) via fkie-cad/nvd-json-data-feedsPublic domain — this product uses data from the NVD API but is not endorsed or certified by the NVD