CVE-2026-64561

HIGHPre-NVD 8.88.8—
EchelonGraph scoreMEDIUM confidence

Score 8.8 from GitHub Security Advisory (severity: HIGH) published 2026-08-04. A secondary CVSS source baseline 8.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this weekElevated
8.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 8.8Exploit: Elevated riskExposed services: Not assessed

A fix is available — apply it.

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

KVM: x86: Check for invalid/obsolete root *after* making MMU pages available

Check for a "stale" page fault, i.e. for an invalid and/or obsolete root, after making MMU pages available for the shadow MMU. If reclaiming shadow pages zaps an in-use root, i.e. marks it invalid, then KVM will attempt to map memory into an invalid root. On its own, populating an invalid root is "fine", but because child shadow pages inherit their parent's role, any children created during the map/fetch will be created as invalid pages, thus violating KVM's invariant that invalid pages are never on the list of active MMU pages.

Note, the underlying flaw has existed since KVM first started tracking invalid roots in 2008 (commit 2e53d63acba7, "KVM: MMU: ignore zapped root pagetables"), but the true badness only came along in 2020 (Linux 5.9) with the invariant that invalid shadow pages can't be on the list of active pages.

Note #2, inheriting role.invalid when creating child shadow pages is also far from ideal; that flaw will be addressed separately.

CVSS v3
8.8
EG Score
8.8HIGHmedium confidence
EG Risk
60
EG Risk 60/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity88% × 45%
Exploitation40% × 40%
Automatability30% × 15%
CISA SSVC: Track at low or medium mission impact; Track* or Attend at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.3%
EPSS %ILE
25th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track* or Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (EG-KEV: elevated) · Automatable unknown (not published for this CVE) · Technical impact partial (CVSS below 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

August 4, 2026

Last Modified

August 27, 2026

Advisory Details (5)

Auto-updated Aug 8, 2026
Patch available.
generic

KVM: x86: Check for invalid/obsolete root *after* making MMU pages available - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/f3477a6a4164f15287444eda685b5f6405dbd1e5
generic

KVM: x86: Check for invalid/obsolete root *after* making MMU pages available - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/bce0d3c26e2c761a4bf43c8949f333fc7374eb2d
generic

KVM: x86: Check for invalid/obsolete root *after* making MMU pages available - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/35e77467610c4a37cb0ff54ee56b85f73b1f5700
generic

KVM: x86: Check for invalid/obsolete root *after* making MMU pages available - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/2abd5287f08319fa35764566b15c6e22cb1068db
generic

KVM: x86: Check for invalid/obsolete root *after* making MMU pages available - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/0026dbb7de8ea76e97d6edf42fc3cc084564e2bf

Vendor Advisories for CVE-2026-64561(11)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(9)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntulinux-tools-nvidia-tegra-rt-6.8 (6.8.0-1035.38) @ noble2026-10-04ubuntu
redhatkernel-0:5.14.0-427.141.1.el9_42026-07-31redhat
redhatkernel-0:5.14.0-570.131.1.el9_62026-07-31redhat
redhatkernel-0:6.12.0-55.94.1.el10_02026-07-31redhat
redhatkernel-0:4.18.0-477.156.1.el8_82026-07-29redhat
redhatkernel-rt-0:4.18.0-553.147.1.rt7.488.el8_102026-07-24redhat
redhatkernel-0:4.18.0-553.147.1.el8_102026-07-24redhat
redhatkernel-0:5.14.0-687.30.1.el9_82026-07-24redhat
redhatkernel-0:6.12.0-211.39.1.el10_22026-07-24redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(5 across 4 ecosystems)
Debian:12(2)
PackageVulnerable rangeFix by version rangeDependents
linux6.1.106-1 ... 6.1.99-1 (56 versions)
  • every version up to 6.1.187-1: fixed in 6.1.187-1
—
linux-6.126.12.100-1~deb12u1
  • every version up to 6.12.101-1~deb12u1: fixed in 6.12.101-1~deb12u1
—
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
linux5.10.103-1 ... 7.2~rc5-1~exp1 (500 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.100-1 ... 6.12.96-1 (32 versions)
  • every version up to 6.12.101-1: fixed in 6.12.101-1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.100-1 ... 7.1~rc7-1~exp1 (161 versions)
  • every version up to 7.1.6-1: fixed in 7.1.6-1
—

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 25× in last 7d / 130× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

Showing the most recent 100 of 320 total refreshes for this CVE.

  1. 2026-10-04 23:43 UTCEG score recompute
  2. 2026-10-04 23:43 UTCVendor advisory
  3. 2026-10-04 23:43 UTCGHSA enrichment
  4. 2026-10-04 23:22 UTCEPSS rescore
  5. 2026-10-04 06:15 UTCEG score recompute
  6. 2026-10-04 06:15 UTCVendor advisory
  7. 2026-10-04 06:15 UTCGHSA enrichment
  8. 2026-10-03 14:26 UTCEPSS rescore
  9. 2026-10-03 02:01 UTCEG score recompute
  10. 2026-10-03 02:01 UTCVendor advisory
  11. 2026-10-03 02:01 UTCGHSA enrichment
  12. 2026-10-02 17:56 UTCEPSS rescore
  13. 2026-10-02 10:14 UTCEG score recompute
  14. 2026-10-02 10:14 UTCVendor advisory
  15. 2026-10-02 10:14 UTCGHSA enrichment
  16. 2026-10-01 19:50 UTCEPSS rescore
  17. 2026-10-01 13:17 UTCVendor advisory
  18. 2026-10-01 13:17 UTCGHSA enrichment
  19. 2026-10-01 02:29 UTCEG score recompute
  20. 2026-10-01 02:29 UTCVendor advisory
  21. 2026-10-01 02:29 UTCGHSA enrichment
  22. 2026-09-30 15:03 UTCEPSS rescore
  23. 2026-09-29 06:28 UTCEG score recompute
  24. 2026-09-29 06:28 UTCVendor advisory
  25. 2026-09-29 06:28 UTCGHSA enrichment
Show 75 more
  1. 2026-09-28 13:51 UTCEPSS rescore
  2. 2026-09-28 05:00 UTCVendor advisory
  3. 2026-09-28 05:00 UTCGHSA enrichment
  4. 2026-09-27 18:07 UTCEG score recompute
  5. 2026-09-27 18:07 UTCVendor advisory
  6. 2026-09-27 18:07 UTCGHSA enrichment
  7. 2026-09-26 15:59 UTCEPSS rescore
  8. 2026-09-25 04:43 UTCEG score recompute
  9. 2026-09-25 04:43 UTCVendor advisory
  10. 2026-09-25 04:43 UTCGHSA enrichment
  11. 2026-09-24 12:50 UTCVendor advisory
  12. 2026-09-24 12:50 UTCGHSA enrichment
  13. 2026-09-24 01:50 UTCEG score recompute
  14. 2026-09-24 01:50 UTCVendor advisory
  15. 2026-09-24 01:50 UTCGHSA enrichment
  16. 2026-09-23 17:54 UTCEPSS rescore
  17. 2026-09-23 15:01 UTCVendor advisory
  18. 2026-09-23 15:01 UTCGHSA enrichment
  19. 2026-09-23 01:59 UTCEG score recompute
  20. 2026-09-23 01:59 UTCVendor advisory
  21. 2026-09-23 01:59 UTCGHSA enrichment
  22. 2026-09-22 15:10 UTCVendor advisory
  23. 2026-09-22 15:10 UTCGHSA enrichment
  24. 2026-09-22 03:30 UTCEG score recompute
  25. 2026-09-22 03:30 UTCVendor advisory
  26. 2026-09-22 03:30 UTCGHSA enrichment
  27. 2026-09-20 20:54 UTCEG score recompute
  28. 2026-09-20 20:54 UTCVendor advisory
  29. 2026-09-20 20:54 UTCGHSA enrichment
  30. 2026-09-20 20:16 UTCEPSS rescore
  31. 2026-09-20 01:45 UTCEG score recompute
  32. 2026-09-20 01:45 UTCVendor advisory
  33. 2026-09-20 01:45 UTCGHSA enrichment
  34. 2026-09-19 14:56 UTCVendor advisory
  35. 2026-09-19 14:56 UTCGHSA enrichment
  36. 2026-09-19 03:41 UTCEG score recompute
  37. 2026-09-19 03:41 UTCVendor advisory
  38. 2026-09-19 03:41 UTCGHSA enrichment
  39. 2026-09-18 19:28 UTCEPSS rescore
  40. 2026-09-18 14:50 UTCVendor advisory
  41. 2026-09-18 14:50 UTCGHSA enrichment
  42. 2026-09-18 03:05 UTCEG score recompute
  43. 2026-09-18 03:05 UTCVendor advisory
  44. 2026-09-18 03:05 UTCGHSA enrichment
  45. 2026-09-17 16:16 UTCVendor advisory
  46. 2026-09-17 16:16 UTCGHSA enrichment
  47. 2026-09-17 01:12 UTCEG score recompute
  48. 2026-09-17 01:12 UTCVendor advisory
  49. 2026-09-17 01:12 UTCGHSA enrichment
  50. 2026-09-16 14:08 UTCEPSS rescore
  51. 2026-09-16 05:16 UTCEG score recompute
  52. 2026-09-16 05:16 UTCVendor advisory
  53. 2026-09-16 05:16 UTCGHSA enrichment
  54. 2026-09-16 05:15 UTCEPSS rescore
  55. 2026-09-15 16:51 UTCEG score recompute
  56. 2026-09-15 16:51 UTCVendor advisory
  57. 2026-09-15 16:50 UTCGHSA enrichment
  58. 2026-09-15 01:43 UTCVendor advisory
  59. 2026-09-15 01:43 UTCGHSA enrichment
  60. 2026-09-14 08:46 UTCVendor advisory
  61. 2026-09-14 08:46 UTCGHSA enrichment
  62. 2026-09-13 21:57 UTCEG score recompute
  63. 2026-09-13 21:57 UTCVendor advisory
  64. 2026-09-13 21:57 UTCGHSA enrichment
  65. 2026-09-13 11:08 UTCVendor advisory
  66. 2026-09-13 11:08 UTCGHSA enrichment
  67. 2026-09-13 00:19 UTCEG score recompute
  68. 2026-09-13 00:19 UTCVendor advisory
  69. 2026-09-13 00:19 UTCGHSA enrichment
  70. 2026-09-12 13:30 UTCVendor advisory
  71. 2026-09-12 13:30 UTCGHSA enrichment
  72. 2026-09-12 02:41 UTCVendor advisory
  73. 2026-09-12 02:41 UTCGHSA enrichment
  74. 2026-09-11 15:52 UTCEG score recompute
  75. 2026-09-11 15:52 UTCVendor advisory

Publicly available exploits

(3 references)

Working exploit code is in the public domain (3 GitHub PoCs). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCHackSpeak/CVE-2026-64561
    First seen Aug 8, 2026

    Zapscape (CVE-2026-64561) KVM/x86 shadow MMU UAF guest-to-host escape PoC mirror — V4bel/@v4bel, MIT; for authorized security testing

    Open source ↗
  • GitHub PoCAoripus-LTD/Zapscape-Fix
    First seen Aug 7, 2026

    Generic kernel live patch for the KVM/x86 shadow-MMU use-after-free (Zapscape, CVE-2026-64561)

    Open source ↗
  • GitHub PoCHORKimhab/CVE-2026-64561
    First seen Aug 7, 2026

    CVE-2026-64561

    Open source ↗

Related CVEs(same vendor)

Frequently asked(5)

What is CVE-2026-64561?
CVE-2026-64561 is a high vulnerability published on August 4, 2026. In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Check for invalid/obsolete root after making MMU pages available Check for a "stale" page fault, i.e. for an invalid and/or obsolete root, after making MMU pages available for the shadow MMU. If reclaiming shadow pages…
When was CVE-2026-64561 disclosed?
CVE-2026-64561 was first published on August 4, 2026, with the most recent update on August 27, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-64561 actively exploited?
CVE-2026-64561 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (25th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-64561?
CVE-2026-64561 has a CVSS base score of 8.8 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-64561?
A fix for CVE-2026-64561 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-64561 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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