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Fencer Vulns
high 8.4

CVE-2024-35875 json

x86/coco: Require seeding RNG with RDRAND on CoCo systems

published 2024-05-19 2 y ago modified 2026-08-05 3 mo ago also EUVD-2024-35593

cvss
8.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 16%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

x86/coco: Require seeding RNG with RDRAND on CoCo systems

There are few uses of CoCo that don't rely on working cryptography and hence a working RNG. Unfortunately, the CoCo threat model means that the VM host cannot be trusted and may actively work against guests to extract secrets or manipulate computation. Since a malicious host can modify or observe nearly all inputs to guests, the only remaining source of entropy for CoCo guests is RDRAND.

If RDRAND is broken -- due to CPU hardware fault -- the RNG as a whole is meant to gracefully continue on gathering entropy from other sources, but since there aren't other sources on CoCo, this is catastrophic. This is mostly a concern at boot time when initially seeding the RNG, as after that the consequences of a broken RDRAND are much more theoretical.

So, try at boot to seed the RNG using 256 bits of RDRAND output. If this fails, panic(). This will also trigger if the system is booted without RDRAND, as RDRAND is essential for a safe CoCo boot.

Add this deliberately to be "just a CoCo x86 driver feature" and not part of the RNG itself. Many device drivers and platforms have some desire to contribute something to the RNG, and add_device_randomness() is specifically meant for this purpose.

Any driver can call it with seed data of any quality, or even garbage quality, and it can only possibly make the quality of the RNG better or have no effect, but can never make it worse.

Rather than trying to build something into the core of the RNG, consider the particular CoCo issue just a CoCo issue, and therefore separate it all out into driver (well, arch/platform) code.

[ bp: Massage commit message. ]

Patch / fix

  • Linux Linux 6.1.85, 6.6.26, 6.8.5, 6.9
  • linux Debian 12 6.1.85-1
  • linux Debian 14, Debian 13 6.8.9-1

debian advisories DEBIAN-CVE-2024-35875

  • linux Ubuntu 24.04 LTS 6.8.0-38.38
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1011.12
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1010.11
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1006.9
  • linux-ibm Ubuntu 24.04 LTS 6.8.0-1008.8
  • linux-azure Ubuntu 24.04 LTS 6.8.0-1010.10
  • linux-intel Ubuntu 24.04 LTS 6.8.0-1007.14
  • linux-raspi Ubuntu 24.04 LTS 6.8.0-1007.7

ubuntu advisories UBUNTU-CVE-2024-35875

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

  • kernel RHEL 9 5.14.0-427.35.1.el9_4
  • rv RHEL 9 5.14.0-427.35.1.el9_4
  • perf RHEL 9 5.14.0-427.35.1.el9_4
  • rtla RHEL 9 5.14.0-427.35.1.el9_4
  • bpftool RHEL 9 7.3.0-427.35.1.el9_4
  • libperf RHEL 9 5.14.0-427.35.1.el9_4
  • kernel-rt RHEL 9 5.14.0-427.35.1.el9_4
  • kernel-64k RHEL 9 5.14.0-427.35.1.el9_4

red hat advisories RHSA-2024:6567RHSA-2024:6267RHSA-2024:6268

  • kernel-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-25.1
  • kernel-source-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-25.1
  • kernel-livepatch-MICRO-6-0-RT_Update_5 Linux Micro 6.1, Linux Micro 6.0 1-1.1
  • kernel-rt Linux Micro 6.0 6.4.0-9.1
  • kernel-source-rt Linux Micro 6.0 6.4.0-9.1
  • kernel-source Linux Micro 6.0 6.4.0-18.1
  • kernel-default Linux Micro 6.0 6.4.0-18.1
  • kernel-kvmsmall Linux Micro 6.0 6.4.0-18.1

suse advisories SUSE-SU-2025:20166-1SUSE-SU-2025:20249-1SUSE-SU-2025:20028-1SUSE-SU-2025:20008-1SUSE-SU-2024:2973-1SUSE-SU-2024:2203-1

  • kernel AlmaLinux 9 5.14.0-427.35.1.el9_4
  • rv AlmaLinux 9 5.14.0-427.35.1.el9_4
  • perf AlmaLinux 9 5.14.0-427.35.1.el9_4
  • rtla AlmaLinux 9 5.14.0-427.35.1.el9_4
  • bpftool AlmaLinux 9 7.3.0-427.35.1.el9_4
  • libperf AlmaLinux 9 5.14.0-427.35.1.el9_4
  • kernel-rt AlmaLinux 9 5.14.0-427.35.1.el9_4
  • kernel-64k AlmaLinux 9 5.14.0-427.35.1.el9_4

almalinux advisories ALSA-2024:6567

  • kernel Rocky Linux 9 5.14.0-427.35.1.el9_4.cloud.1.0
  • kernel Rocky Linux 9 5.14.0-427.35.1.el9_4

rocky linux advisories RXSA-2024:6567RLSA-2024:6567

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-2024-35875 updated cvss 5.5

kernel: x86/coco: Require seeding RNG with RDRAND on CoCo systems

  • Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more
    affected: no fix planned “Will not fix”
  • Red Hat Enterprise Linux 9 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 more
    affected: no fix available
  • Red Hat CodeReady Linux Builder EUS (v.9.2) kernel-debuginfo-common-s390x 5.14.0-284.82.1.el9_2, kernel-debuginfo-common-x86_64 5.14.0-284.82.1.el9_2, kernel-debuginfo-common-aarch64 5.14.0-284.82.1.el9_2, kernel-debuginfo-common-ppc64le 5.14.0-284.82.1.el9_2
    fixed: vendor fix RHSA-2024:6267
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-427.35.1.el9_4, perf 5.14.0-427.35.1.el9_4, rtla 5.14.0-427.35.1.el9_4, kernel-devel-matched 5.14.0-427.35.1.el9_4, kernel-64k-devel-matched 5.14.0-427.35.1.el9_4, kernel-debug-devel-matched 5.14.0-427.35.1.el9_4, +6 more
    fixed: vendor fix RHSA-2024:6567
  • Red Hat Enterprise Linux AppStream EUS (v.9.2) perf 5.14.0-284.82.1.el9_2, rtla 5.14.0-284.82.1.el9_2, kernel-devel-matched 5.14.0-284.82.1.el9_2, kernel-64k-devel-matched 5.14.0-284.82.1.el9_2, kernel-debug-devel-matched 5.14.0-284.82.1.el9_2, kernel-debuginfo-common-s390x 5.14.0-284.82.1.el9_2, +5 more
    fixed: vendor fix RHSA-2024:6267
  • Red Hat Enterprise Linux BaseOS (v. 9) bpftool 7.3.0-427.35.1.el9_4, kernel 5.14.0-427.35.1.el9_4, kernel-64k 5.14.0-427.35.1.el9_4, kernel-core 5.14.0-427.35.1.el9_4, kernel-tools 5.14.0-427.35.1.el9_4, python3-perf 5.14.0-427.35.1.el9_4, +28 more
    fixed: vendor fix RHSA-2024:6567
  • Red Hat Enterprise Linux BaseOS EUS (v.9.2) bpftool 7.0.0-284.82.1.el9_2, kernel 5.14.0-284.82.1.el9_2, kernel-64k 5.14.0-284.82.1.el9_2, kernel-core 5.14.0-284.82.1.el9_2, kernel-tools 5.14.0-284.82.1.el9_2, python3-perf 5.14.0-284.82.1.el9_2, +28 more
    fixed: vendor fix RHSA-2024:6267
  • Red Hat Enterprise Linux CRB (v. 9) libperf 5.14.0-427.35.1.el9_4, kernel-debuginfo-common-s390x 5.14.0-427.35.1.el9_4, kernel-debuginfo-common-x86_64 5.14.0-427.35.1.el9_4, kernel-debuginfo-common-aarch64 5.14.0-427.35.1.el9_4, kernel-debuginfo-common-ppc64le 5.14.0-427.35.1.el9_4 Red Hat Enterprise Linux NFV (v. 9) kernel-rt 5.14.0-427.35.1.el9_4, kernel-rt-kvm 5.14.0-427.35.1.el9_4, kernel-rt-core 5.14.0-427.35.1.el9_4, kernel-rt-modules 5.14.0-427.35.1.el9_4, kernel-rt-debug-kvm 5.14.0-427.35.1.el9_4, kernel-rt-debug-core 5.14.0-427.35.1.el9_4, +6 more
    fixed: vendor fix RHSA-2024:6567
show 3 more
  • Red Hat Enterprise Linux Real Time EUS (v.9.2) kernel-rt 5.14.0-284.82.1.rt14.367.el9_2, kernel-rt-core 5.14.0-284.82.1.rt14.367.el9_2, kernel-rt-modules 5.14.0-284.82.1.rt14.367.el9_2, kernel-rt-debug-core 5.14.0-284.82.1.rt14.367.el9_2, kernel-rt-modules-core 5.14.0-284.82.1.rt14.367.el9_2, kernel-rt-debug-modules 5.14.0-284.82.1.rt14.367.el9_2, +4 more Red Hat Enterprise Linux Real Time for NFV EUS (v.9.2) kernel-rt 5.14.0-284.82.1.rt14.367.el9_2, kernel-rt-kvm 5.14.0-284.82.1.rt14.367.el9_2, kernel-rt-core 5.14.0-284.82.1.rt14.367.el9_2, kernel-rt-modules 5.14.0-284.82.1.rt14.367.el9_2, kernel-rt-debug-kvm 5.14.0-284.82.1.rt14.367.el9_2, kernel-rt-debug-core 5.14.0-284.82.1.rt14.367.el9_2, +6 more
    fixed: vendor fix RHSA-2024:6268
  • Red Hat Enterprise Linux RT (v. 9) kernel-rt 5.14.0-427.35.1.el9_4, kernel-rt-core 5.14.0-427.35.1.el9_4, kernel-rt-modules 5.14.0-427.35.1.el9_4, kernel-rt-debug-core 5.14.0-427.35.1.el9_4, kernel-rt-modules-core 5.14.0-427.35.1.el9_4, kernel-rt-debug-modules 5.14.0-427.35.1.el9_4, +4 more
    fixed: vendor fix RHSA-2024:6567
  • 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 Red Hat Enterprise Linux AppStream EUS (v.9.2) kernel-doc 5.14.0-284.82.1.el9_2
    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 SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.25% chance of exploitation in the next 30 days, higher than 16% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 8.4 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

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.