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Fencer Vulns
medium 4.7

CVE-2023-0045 json

Incorrect indirect branch prediction barrier in the Linux Kernel

published 2023-04-25 3 y ago modified 2026-06-17 4 mo ago also EUVD-2023-12148

cvss
4.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.4%
EPSS 2.4% chance of exploitation in 30 days, percentile 84%
public exploits
0
none known

Summary

The current implementation of the prctl syscall does not issue an IBPB immediately during the syscall. The ib_prctl_set  function updates the Thread Information Flags (TIFs) for the task and updates the SPEC_CTRL MSR on the function __speculation_ctrl_update, but the IBPB is only issued on the next schedule, when the TIF bits are checked. This leaves the victim vulnerable to values already injected on the BTB, prior to the prctl syscall.  The patch that added the support for the conditional mitigation via prctl (ib_prctl_set) dates back to the kernel 4.9.176.

We recommend upgrading past commit a664ec9158eeddd75121d39c9a0758016097fa96

Patch / fix

  • linux linux_kernel 3.17, 4.5, 4.10, 4.14.303, 4.19.270, 5.4.229, 5.10.163, 5.15.87, 6.0.19, 6.1.5
  • linux Debian 14, Debian 13, Debian 12 6.1.7-1

debian advisories DEBIAN-CVE-2023-0045

  • linux Ubuntu 18.04 LTS 4.15.0-208.220
  • linux Ubuntu 20.04 LTS 5.4.0-144.161
  • linux Ubuntu 22.04 LTS 5.15.0-69.76
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1153.166
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1097.105
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1033.37
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1101.110
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1031.38

ubuntu advisories UBUNTU-CVE-2023-0045

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • dtb-aarch64 openSUSE Leap 15.5 5.14.21-150500.55.7.1
  • kernel-64kb SLE Module for Basesystem 15 SP5, openSUSE Leap 15.5 5.14.21-150500.55.7.1
  • kernel-syms SLE Module for Development Tools 15 SP5, openSUSE Leap 15.5 5.14.21-150500.55.7.1
  • kernel-obs-qa openSUSE Leap 15.5 5.14.21-150500.55.7.1
  • kernel-source SLE Module for Development Tools 15 SP5, SLE Module for Basesystem 15 SP5, openSUSE Leap 15.5 5.14.21-150500.55.7.1
  • kernel-default SLE Workstation Extension 15 SP5, SLE Module for Legacy 15 SP5, SLE Module for Basesystem 15 SP5 +3 more 5.14.21-150500.55.7.1
  • kernel-kvmsmall openSUSE Leap 15.5 5.14.21-150500.55.7.1
  • kernel-zfcpdump SLE Module for Basesystem 15 SP5, openSUSE Leap 15.5 5.14.21-150500.55.7.1

suse advisories SUSE-SU-2023:2871-1SUSE-SU-2023:2809-1SUSE-SU-2023:0618-1SUSE-SU-2023:2646-1SUSE-SU-2023:1710-1SUSE-SU-2023:1608-1

  • kernel-source openSUSE Tumbleweed 6.1.12-1.1
  • kernel-source openSUSE Tumbleweed 6.6.17-1.1

opensuse advisories openSUSE-SU-2024:12697-1openSUSE-SU-2024:13704-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2023-0045 updated cvss 4.7

kernel: Bypassing Spectre-BTI User Space Mitigations

  • Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more
    affected: workaround, no fix available “For user-mode applications, a usleep after the prctl call will force a reschedule and ensure the correct mitigation.”
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

cisa ICSA-25-044-09 updated cvss 4.7

Siemens SCALANCE W700 IEEE 802.11ax

  • Siemens SCALANCE WAB762-1 (6GK5762-1AJ00-6AA0) <V3.0.0 Siemens SCALANCE WAM763-1 (6GK5763-1AL00-7DA0) <V3.0.0 Siemens SCALANCE WAM763-1 (ME) (6GK5763-1AL00-7DC0) <V3.0.0 Siemens SCALANCE WAM763-1 (US) (6GK5763-1AL00-7DB0) <V3.0.0 Siemens SCALANCE WAM766-1 (6GK5766-1GE00-7DA0) <V3.0.0 Siemens SCALANCE WAM766-1 (ME) (6GK5766-1GE00-7DC0) <V3.0.0
    +13 more products
    Siemens SCALANCE WAM766-1 (US) (6GK5766-1GE00-7DB0) <V3.0.0 Siemens SCALANCE WAM766-1 EEC (6GK5766-1GE00-7TA0) <V3.0.0 Siemens SCALANCE WAM766-1 EEC (ME) (6GK5766-1GE00-7TC0) <V3.0.0 Siemens SCALANCE WAM766-1 EEC (US) (6GK5766-1GE00-7TB0) <V3.0.0 Siemens SCALANCE WUB762-1 (6GK5762-1AJ00-1AA0) <V3.0.0 Siemens SCALANCE WUB762-1 iFeatures (6GK5762-1AJ00-2AA0) <V3.0.0 Siemens SCALANCE WUM763-1 (6GK5763-1AL00-3AA0) <V3.0.0 Siemens SCALANCE WUM763-1 (6GK5763-1AL00-3DA0) <V3.0.0 Siemens SCALANCE WUM763-1 (US) (6GK5763-1AL00-3AB0) <V3.0.0 Siemens SCALANCE WUM763-1 (US) (6GK5763-1AL00-3DB0) <V3.0.0 Siemens SCALANCE WUM766-1 (6GK5766-1GE00-3DA0) <V3.0.0 Siemens SCALANCE WUM766-1 (ME) (6GK5766-1GE00-3DC0) <V3.0.0 Siemens SCALANCE WUM766-1 (USA) (6GK5766-1GE00-3DB0) <V3.0.0
    affected: fixed in V3.0.0 support.industry.siemens.com

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
21 mo ago

Exploit prediction

2.40% chance of exploitation in the next 30 days, higher than 84% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/google/security-research/security/advisories/GHSA-9x5g-vmxf-4qj8 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 4.7 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected products

  • Linux Linux Kernel

Classification

Weakness
  • CWE-610 Externally Controlled Reference to a Resource in Another Sphere
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.