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%CVSS: 8.8Exploit: Elevated riskExposed: 0

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
8.8(medium)
EG Risk
60(Track)
EG Risk 60/100SSVC: Track

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%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
28%
KEV
Not listed

Published

August 4, 2026

Last Modified

August 27, 2026

Advisory Details (5)

Auto-updated Aug 8, 2026
No patch confirmed yet.
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 / EcosystemFixed in / PatchReleasedSource
ubuntulinux-tools-nvidia-tegra-rt-6.8 (6.8.0-1035.38) @ noble2026-09-19ubuntu
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 rangeFixed inDependents
linux6.1.106-1 ... 6.1.99-1 (56 versions)6.1.187-1—
linux-6.126.12.100-1~deb12u16.12.101-1~deb12u1—
Debian:11(1)
PackageVulnerable rangeFixed inDependents
linux5.10.103-1 ... 7.2~rc5-1~exp1 (500 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
linux6.12.100-1 ... 6.12.96-1 (32 versions)6.12.101-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
linux6.12.100-1 ... 7.1~rc7-1~exp1 (160 versions)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 36× in last 7d / 159× 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 260 total refreshes for this CVE.

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

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 PoCHORKimhab/CVE-2026-64561
    First seen Aug 7, 2026

    CVE-2026-64561

    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 ↗

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 in the National Vulnerability Database 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% probability of exploitation in the next 30 days, which ranks it in the top 71.7% of all scored CVEs.
What is the CVSS score of CVE-2026-64561?
CVE-2026-64561 has a CVSS v3 base score of 8.8 (NVD).
How do I remediate CVE-2026-64561?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-64561, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-64561

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