CVE-2021-47230

MEDIUMNVD 6.66.6
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to NVD's CVSS score.

Score 6.6 from GitHub Security Advisory published 2024-05-21. NVD baseline CVSS 6.6; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3

Also known asEUVD-2021-33878 (ENISA EUVD) · GHSA-j8hx-6rxw-p4r9 (GitHub Security Advisories)Source: ENISA EUVD

6.6EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 6.6Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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

KVM: x86: Immediately reset the MMU context when the SMM flag is cleared

Immediately reset the MMU context when the vCPU's SMM flag is cleared so that the SMM flag in the MMU role is always synchronized with the vCPU's flag. If RSM fails (which isn't correctly emulated), KVM will bail without calling post_leave_smm() and leave the MMU in a bad state.

The bad MMU role can lead to a NULL pointer dereference when grabbing a shadow page's rmap for a page fault as the initial lookups for the gfn will happen with the vCPU's SMM flag (=0), whereas the rmap lookup will use the shadow page's SMM flag, which comes from the MMU (=1). SMM has an entirely different set of memslots, and so the initial lookup can find a memslot (SMM=0) and then explode on the rmap memslot lookup (SMM=1).

general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 1 PID: 8410 Comm: syz-executor382 Not tainted 5.13.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__gfn_to_rmap arch/x86/kvm/mmu/mmu.c:935 [inline] RIP: 0010:gfn_to_rmap+0x2b0/0x4d0 arch/x86/kvm/mmu/mmu.c:947 Code: <42> 80 3c 20 00 74 08 4c 89 ff e8 f1 79 a9 00 4c 89 fb 4d 8b 37 44 RSP: 0018:ffffc90000ffef98 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff888015b9f414 RCX: ffff888019669c40 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000001 RBP: 0000000000000001 R08: ffffffff811d9cdb R09: ffffed10065a6002 R10: ffffed10065a6002 R11: 0000000000000000 R12: dffffc0000000000 R13: 0000000000000003 R14: 0000000000000001 R15: 0000000000000000 FS: 000000000124b300(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 0000000028e31000 CR4: 00000000001526e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: rmap_add arch/x86/kvm/mmu/mmu.c:965 [inline] mmu_set_spte+0x862/0xe60 arch/x86/kvm/mmu/mmu.c:2604 __direct_map arch/x86/kvm/mmu/mmu.c:2862 [inline] direct_page_fault+0x1f74/0x2b70 arch/x86/kvm/mmu/mmu.c:3769 kvm_mmu_do_page_fault arch/x86/kvm/mmu.h:124 [inline] kvm_mmu_page_fault+0x199/0x1440 arch/x86/kvm/mmu/mmu.c:5065 vmx_handle_exit+0x26/0x160 arch/x86/kvm/vmx/vmx.c:6122 vcpu_enter_guest+0x3bdd/0x9630 arch/x86/kvm/x86.c:9428 vcpu_run+0x416/0xc20 arch/x86/kvm/x86.c:9494 kvm_arch_vcpu_ioctl_run+0x4e8/0xa40 arch/x86/kvm/x86.c:9722 kvm_vcpu_ioctl+0x70f/0xbb0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3460 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:1069 [inline] __se_sys_ioctl+0xfb/0x170 fs/ioctl.c:1055 do_syscall_64+0x3f/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x440ce9

CVSS v3
6.6
EG Score
6.6MEDIUMmedium confidence
EG Risk
30
EG Risk 30/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity66% × 45%
Impact severity (EG Severity): CVSS 6.6 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.2% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.2%
EPSS %ILE
14th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (6.6): severity, escalated by confirmed exploitation. This CVE's 6.6 is its impact severity (EG Severity), not escalated.

EG Severity
6.6 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-25). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

May 21, 2024

Last Modified

April 4, 2025

Advisory Details (4)

Auto-updated Oct 24, 2026
Patch available.
Web page

KVM: x86: Immediately reset the MMU context when the SMM flag is cleared - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/df9a40cfb3be2cbeb1c17bb67c59251ba16630f3
Web page

KVM: x86: Immediately reset the MMU context when the SMM flag is cleared - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/cbb425f62df9df7abee4b3f068f7ed6ffc3561e2
Web page

KVM: x86: Immediately reset the MMU context when the SMM flag is cleared - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/78fcb2c91adfec8ce3a2ba6b4d0dda89f2f4a7c6
Web page

KVM: x86: Immediately reset the MMU context when the SMM flag is cleared - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/669a8866e468fd020d34eb00e08cb41d3774b71b

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
linux—
  • every version up to 5.10.46-1: fixed in 5.10.46-1
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
linux—
  • every version up to 5.10.46-1: fixed in 5.10.46-1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
linux—
  • every version up to 5.10.46-1: fixed in 5.10.46-1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
linux—
  • every version up to 5.10.46-1: fixed in 5.10.46-1
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 7× in last 7d / 37× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 97 of 208 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 3 repeat rows among the latest 100 are merged into the row they repeat. The 111 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-02 16:38 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  2. 2026-11-01 16:30 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  3. 2026-10-31 16:29 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  4. 2026-10-30 16:30 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  5. 2026-10-29 16:29 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  6. 2026-10-28 16:28 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  7. 2026-10-27 16:28 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  8. 2026-10-26 16:28 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  9. 2026-10-25 18:18 UTCEG score recompute
  10. 2026-10-25 16:29 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  11. 2026-10-24 21:47 UTCEG score recompute
  12. 2026-10-24 21:47 UTCGHSA enrichmentGHSA-j8hx-6rxw-p4r9 · GitHub CVSS 6.6
  13. 2026-10-24 16:29 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  14. 2026-10-23 16:28 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  15. 2026-10-22 16:29 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  16. 2026-10-21 16:28 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  17. 2026-10-20 16:28 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  18. 2026-10-19 16:28 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  19. 2026-10-18 16:28 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  20. 2026-10-18 08:49 UTCEG score recompute
  21. 2026-10-17 16:29 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  22. 2026-10-16 16:34 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  23. 2026-10-15 16:28 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  24. 2026-10-14 16:29 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  25. 2026-10-13 16:28 UTCEPSS rescoreEPSS 0.2% · 13th percentile
Show 72 more
  1. 2026-10-12 19:05 UTCEG score recompute
  2. 2026-10-12 16:30 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  3. 2026-10-11 23:31 UTCEG score recompute
  4. 2026-10-11 13:44 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  5. 2026-10-11 01:22 UTCOSV refresh
  6. 2026-10-10 19:56 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  7. 2026-10-09 20:04 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  8. 2026-10-08 16:40 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  9. 2026-10-07 23:45 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  10. 2026-10-06 15:14 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  11. 2026-10-05 17:40 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  12. 2026-10-04 23:19 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  13. 2026-10-03 14:22 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  14. 2026-10-02 16:23 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  15. 2026-09-30 15:45 UTCEG score recompute
  16. 2026-09-30 15:00 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  17. 2026-09-29 15:15 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  18. 2026-09-28 13:47 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  19. 2026-09-26 15:54 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  20. 2026-09-26 00:21 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  21. 2026-09-24 14:00 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  22. 2026-09-23 13:45 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  23. 2026-09-22 14:44 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  24. 2026-09-21 20:28 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  25. 2026-09-21 12:49 UTCOSV refresh
  26. 2026-09-20 20:13 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  27. 2026-09-19 15:38 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  28. 2026-09-18 19:24 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  29. 2026-09-17 19:23 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  30. 2026-09-16 14:05 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  31. 2026-09-15 03:06 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  32. 2026-09-12 14:57 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  33. 2026-09-11 14:49 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  34. 2026-09-11 09:33 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  35. 2026-09-08 21:57 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  36. 2026-09-07 15:58 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  37. 2026-09-06 13:45 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  38. 2026-09-05 15:25 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  39. 2026-09-04 13:57 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  40. 2026-09-04 05:03 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  41. 2026-09-02 14:09 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  42. 2026-09-02 10:14 UTCOSV refresh
  43. 2026-09-01 13:51 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  44. 2026-08-30 19:14 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  45. 2026-08-30 01:19 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  46. 2026-08-28 21:38 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  47. 2026-08-27 14:22 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  48. 2026-08-26 14:43 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  49. 2026-08-25 13:46 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  50. 2026-08-24 14:13 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  51. 2026-08-21 23:46 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  52. 2026-08-20 22:52 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  53. 2026-08-19 17:01 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  54. 2026-08-18 13:45 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  55. 2026-08-17 13:44 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  56. 2026-08-16 14:53 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  57. 2026-08-16 08:47 UTCOSV refresh
  58. 2026-08-16 02:11 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  59. 2026-08-15 01:27 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  60. 2026-08-13 21:57 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  61. 2026-08-12 13:48 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  62. 2026-08-11 13:38 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  63. 2026-08-09 13:44 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  64. 2026-08-08 16:34 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  65. 2026-08-07 16:24 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  66. 2026-08-06 13:44 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  67. 2026-08-05 19:15 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  68. 2026-08-04 15:06 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  69. 2026-08-04 10:34 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  70. 2026-08-03 10:33 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  71. 2026-08-02 02:24 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  72. 2026-08-01 04:13 UTCEPSS rescoreEPSS 0.2% · 14th percentile

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2021-47230?
CVE-2021-47230 is a medium-severity vulnerability; its CVE record was published on May 21, 2024. In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Immediately reset the MMU context when the SMM flag is cleared Immediately reset the MMU context when the vCPU's SMM flag is cleared so that the SMM flag in the MMU role is always synchronized with the vCPU's flag. If RSM…
When was the CVE record for CVE-2021-47230 published?
The CVE record for CVE-2021-47230 was published on May 21, 2024. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of April 4, 2025; the record at its source may have been updated since.
Is CVE-2021-47230 actively exploited?
CVE-2021-47230 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (14th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2021-47230?
CVE-2021-47230 has a CVSS v3 base score of 6.6 (NVD).
How do I remediate CVE-2021-47230?
A fix for CVE-2021-47230 is available: update to the fixed version the vendor names in its advisory.

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