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TI-2020-07091 Aliases CVE-2020-8834GHSA-7fx7-755p-qmjj

Linux kernel KVM Power8 conflicting use of HSTATE_HOST_R1

Priority LOW 29CWE-368Published · Updated

Key facts

Attack vector
Local
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
None · None · High
Fix status
Partial Red Hat: 2 fixed, 1 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.

Summary

KVM in the Linux kernel on Power8 processors has a conflicting use of HSTATE_HOST_R1 to store r1 state in kvmppc_hv_entry plus in kvmppc_{save,restore}_tm, leading to a stack corruption. Because of this, an attacker with the ability run code in kernel space of a guest VM can cause the host kernel to panic. There were two commits that, according to the reporter, introduced the vulnerability: f024ee098476 ("KVM: PPC: Book3S HV: Pull out TM state save/restore into separate procedures") 87a11bb6a7f7 ("KVM: PPC: Book3S HV: Work around XER[SO] bug in fake suspend mode") The former landed in 4.8, the latter in 4.17. This was fixed without realizing the impact in 4.18 with the following three commits, though it's believed the first is the only strictly necessary commit: 6f597c6b63b6 ("KVM: PPC: Book3S PR: Add guest MSR parameter for kvmppc_save_tm()/kvmppc_restore_tm()") 7b0e827c6970 ("KVM: PPC: Book3S HV: Factor fake-suspend handling out of kvmppc_save/restore_tm") 009c872a8bc4 ("KVM: PPC: Book3S PR: Move kvmppc_save_tm/kvmppc_restore_tm to separate file")

Why it matters now

EPSS 0.00347 28th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Partial Linux kernel (Linux kernel): 4.18Red Hat: 1 advisoryRed Hat: 2 fixed, 1 without a fix

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
LinuxLinux kernel4.8 and later; before 4.184.18Patch availableCNA
  • Linux kernel VendorLinux Affected 4.8 and later; before 4.18 Fixed in 4.18 Patch available CNA

CPE configurations NVD · 5

CPEVersionsRoleVendor
cpe:2.3:o:linux:linux_kernel:-:*:*:*:*:*:*:*not specified by NVDVulnerableLinux
cpe:2.3:h:ibm:power8:-:*:*:*:*:*:*:*not specified by NVDRunning onIBM
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*16.04VulnerableCanonical
cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*18.04VulnerableCanonical
cpe:2.3:o:opensuse:leap:15.1:*:*:*:*:*:*:*15.1VulnerableopenSUSE
  • cpe:2.3:o:linux:linux_kernel:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Linux
  • cpe:2.3:h:ibm:power8:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·IBM
  • cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:* Versions 16.04 Vulnerable ·Canonical
  • cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:* Versions 18.04 Vulnerable ·Canonical
  • cpe:2.3:o:opensuse:leap:15.1:*:*:*:*:*:*:* Versions 15.1 Vulnerable ·openSUSE

Remediation

  • Fix · CNA Linux kernel (Linux kernel) Fixed in 4.18

Red Hat 1 advisory

  • RHSA-2020:2854 Released 2020-07-07 · Red Hat rating Important
    kernel-alt security and bug fix update
    • Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server (v. 7) kernel-4.14.0-115.26.1.el7a, kernel-abi-whitelists-4.14.0-115.26.1.el7a, kernel-alt-4.14.0-115.26.1.el7a +8
    • Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server Optional (v. 7) kernel-debug-devel-4.14.0-115.26.1.el7a, kernel-tools-libs-devel-4.14.0-115.26.1.el7a

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 7AffectedNo fix yet
Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server (v. 7)Fixed RHSA-2020:2854
Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server Optional (v. 7)Fixed RHSA-2020:2854
Not affected: 6 products
  • Red Hat Enterprise Linux 5
  • Red Hat Enterprise Linux 6
  • Red Hat Enterprise Linux 7
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server (v. 7)
  • Red Hat Enterprise MRG 2

Timeline

  1. 2026-10-02 Threatist record created from CVE-2020-8834
  2. 2026-10-03 Alias added: GHSA-7fx7-755p-qmjj

References

Exploit 1

Advisory 4

  • TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
  • TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
  • TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
  • TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
  • TI-2021-05514 Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE KEVCVSS 3.1HIGH 8.3
See all 15278 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences