CVE-2025-40300

MEDIUMNVD 5.55.5—
EchelonGraph scoreMEDIUM confidence

Score 5.5 from GitHub Security Advisory published 2025-09-11. NVD baseline CVSS 5.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
5.5
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.5Exploit: NoneExposed: 0

A fix is available — apply it.

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

x86/vmscape: Add conditional IBPB mitigation

VMSCAPE is a vulnerability that exploits insufficient branch predictor isolation between a guest and a userspace hypervisor (like QEMU). Existing mitigations already protect kernel/KVM from a malicious guest. Userspace can additionally be protected by flushing the branch predictors after a VMexit.

Since it is the userspace that consumes the poisoned branch predictors, conditionally issue an IBPB after a VMexit and before returning to userspace. Workloads that frequently switch between hypervisor and userspace will incur the most overhead from the new IBPB.

This new IBPB is not integrated with the existing IBPB sites. For instance, a task can use the existing speculation control prctl() to get an IBPB at context switch time. With this implementation, the IBPB is doubled up: one at context switch and another before running userspace.

The intent is to integrate and optimize these cases post-embargo.

[ dhansen: elaborate on suboptimal IBPB solution ]

CVSS v3
5.5
EG Score
5.5(medium)
EG Risk
—
EPSS
25.5%
KEV
Not listed

Published

September 11, 2025

Last Modified

July 14, 2026

Advisory Details (10)

Auto-updated Jul 19, 2026
No patch confirmed yet.
generic

x86/vmscape: Enable the mitigation - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/c08192b5d6730a914dee6175bc71092ee6a65f14
generic

x86/vmscape: Add conditional IBPB mitigation - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/ac60717f9a8d21c58617d0b34274babf24135835
generic

x86/vmscape: Enable the mitigation - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/9c23a90648e831d611152ac08dbcd1283d405e7f
generic

x86/vmscape: Enable the mitigation - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/893387c18612bb452336a5881da0d015a7e8f4a2
generic

x86/vmscape: Add conditional IBPB mitigation - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/510603f504796c3535f67f55fb0b124a303b44c8
generic

x86/vmscape: Enable the mitigation - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/459274c77b37ac63b78c928b4b4e748d1f9d05c8
generic

x86/vmscape: Enable the mitigation - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/34e5667041050711a947e260fc9ebebe08bddee5
generic

x86/vmscape: Add conditional IBPB mitigation - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/2f8f173413f1cbf52660d04df92d0069c4306d25
generic

x86/vmscape: Enable the mitigation - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/2f4f2f8f860cb4c3336a7435ebe8dcfded0c9c6e
generic

x86/vmscape: Add conditional IBPB mitigation - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/15006289e5c38b2a830e1fba221977a27598176c

Vendor Advisories for CVE-2025-40300(13)

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

Patch Availability(31)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-tools-gcp-fips-5.15 (5.15.0.1096.86) @ jammy2026-05-21ubuntu
ubuntulinux-tools-oracle-lts-24.04 (6.8.0-1039.40) @ noble2026-05-21ubuntu
ubuntulinux-tools-realtime-5.15 (5.15.0.1095.99) @ jammy2026-05-21ubuntu
ubuntulinux-tools-azure-edge (4.15.0.1194.209~16.04.1) @ xenial2026-05-21ubuntu
ubuntulinux-tools-raspi-nolpae (5.15.0.1090.88) @ jammy2026-05-21ubuntu
ubuntulinux-virtual-hwe-24.04-edge (6.14.0-35.35~24.04.1) @ noble2026-05-21ubuntu
ubuntulinux-xilinx-zynqmp-tools-5.15.0-1060 (5.15.0-1060.64) @ jammy2026-05-21ubuntu
ubuntulinux-tools-azure-lts-24.04 (6.8.0-1044.50) @ noble2026-05-21ubuntu
ubuntulinux-tools-azure-fips-4.15 (4.15.0.2104.100) @ bionic2026-05-21ubuntu
ubuntulinux-tools-azure-edge (5.15.0.1102.111~20.04.1) @ focal2026-05-21ubuntu
ubuntulinux-tools-azure-fips-5.4 (5.4.0.1157.94) @ focal2026-05-21ubuntu
ubuntulinux-tools-azure-lts-22.04 (5.15.0.1101.99) @ jammy2026-05-21ubuntu
ubuntulinux-tools-gcp-fips-5.4 (5.4.0.1155.97) @ focal2026-05-21ubuntu
ubuntulinux-tools-oracle (4.15.0.1148.159~16.04.1) @ xenial2026-05-21ubuntu
ubuntulinux-tools-iot-5.4 (5.4.0.1056.54) @ focal2026-05-21ubuntu
ubuntulinux-xilinx-zynqmp-tools-5.4.0-1070 (5.4.0-1070.74) @ focal2026-05-21ubuntu
ubuntulinux-tools-aws-edge (6.8.0-1042.44~22.04.1) @ jammy2026-05-21ubuntu
redhatkernel-0:6.12.0-55.52.1.el10_02026-01-08redhat
redhatkernel-0:5.14.0-284.148.1.el9_22025-11-25redhat
redhatkernel-rt-0:5.14.0-284.148.1.rt14.433.el9_22025-11-25redhat
redhatkernel-0:4.18.0-372.170.1.el8_62025-11-25redhat
redhatkernel-rt-0:5.14.0-70.155.1.rt21.227.el9_02025-11-25redhat
redhatkernel-0:4.18.0-477.120.1.el8_82025-11-25redhat
redhatkernel-0:5.14.0-70.155.1.el9_02025-11-25redhat
redhatkernel-0:5.14.0-427.100.1.el9_42025-11-19redhat
redhatkernel-0:6.12.0-124.9.1.el10_12025-11-12redhat
redhatkernel-0:5.14.0-611.7.1.el9_72025-11-12redhat
redhatkernel-0:5.14.0-570.62.1.el9_62025-11-10redhat
redhatkernel-rt-0:4.18.0-553.83.1.rt7.424.el8_102025-11-10redhat
redhatkernel-0:4.18.0-553.83.1.el8_102025-11-10redhat
linuxKernel @ 5.10.244—osv

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.

Additional Vendor Advisories

(13)

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 11× in last 7d / 49× 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 123 total refreshes for this CVE.

  1. 2026-07-22 14:07 UTCEPSS rescore
  2. 2026-07-22 14:07 UTCEPSS rescore
  3. 2026-07-21 15:24 UTCEPSS rescore
  4. 2026-07-20 17:07 UTCEPSS rescore
  5. 2026-07-19 14:30 UTCEPSS rescore
  6. 2026-07-19 14:30 UTCEPSS rescore
  7. 2026-07-19 02:28 UTCEPSS rescore
  8. 2026-07-19 02:28 UTCEPSS rescore
  9. 2026-07-18 10:04 UTCEPSS rescore
  10. 2026-07-18 10:04 UTCEPSS rescore
  11. 2026-07-16 17:02 UTCEPSS rescore
  12. 2026-07-15 16:57 UTCEPSS rescore
  13. 2026-07-15 16:57 UTCEPSS rescore
  14. 2026-07-15 01:59 UTCEPSS rescore
  15. 2026-07-15 01:59 UTCEPSS rescore
  16. 2026-07-14 13:19 UTCNVD updateCVSS v3 → 5.5 · severity → MEDIUM
  17. 2026-07-13 22:29 UTCEPSS rescore
  18. 2026-07-13 22:29 UTCEPSS rescore
  19. 2026-07-13 06:12 UTCEPSS rescore
  20. 2026-07-12 05:46 UTCEPSS rescore
  21. 2026-07-11 08:27 UTCEPSS rescore
  22. 2026-07-11 08:27 UTCEPSS rescore
  23. 2026-07-10 06:53 UTCOSV refresh
  24. 2026-07-09 19:09 UTCEPSS rescore
  25. 2026-07-09 19:09 UTCEPSS rescore
Show 75 more
  1. 2026-07-07 13:45 UTCEPSS rescore
  2. 2026-07-06 16:27 UTCEPSS rescore
  3. 2026-07-06 16:27 UTCEPSS rescore
  4. 2026-07-06 02:23 UTCEPSS rescore
  5. 2026-07-05 02:30 UTCEPSS rescore
  6. 2026-07-04 06:30 UTCEPSS rescore
  7. 2026-07-01 15:06 UTCEPSS rescore
  8. 2026-07-01 15:06 UTCEPSS rescore
  9. 2026-06-30 23:22 UTCEPSS rescore
  10. 2026-06-30 23:22 UTCEPSS rescore
  11. 2026-06-29 14:06 UTCEPSS rescore
  12. 2026-06-29 14:06 UTCEPSS rescore
  13. 2026-06-28 14:07 UTCEPSS rescore
  14. 2026-06-28 14:07 UTCEPSS rescore
  15. 2026-06-28 04:55 UTCEPSS rescore
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  17. 2026-06-27 03:08 UTCEPSS rescore
  18. 2026-06-27 03:08 UTCEPSS rescore
  19. 2026-06-25 13:49 UTCEPSS rescore
  20. 2026-06-25 13:49 UTCEPSS rescore
  21. 2026-06-24 14:04 UTCEPSS rescore
  22. 2026-06-24 14:04 UTCEPSS rescore
  23. 2026-06-23 21:32 UTCEPSS rescore
  24. 2026-06-23 21:32 UTCEPSS rescore
  25. 2026-06-22 14:25 UTCEPSS rescore
  26. 2026-06-22 14:25 UTCEPSS rescore
  27. 2026-06-21 16:42 UTCOSV refresh
  28. 2026-06-21 14:56 UTCEPSS rescore
  29. 2026-06-21 14:56 UTCEPSS rescore
  30. 2026-06-21 01:59 UTCEPSS rescore
  31. 2026-06-21 01:59 UTCEPSS rescore
  32. 2026-06-19 19:25 UTCEPSS rescore
  33. 2026-06-19 19:25 UTCEPSS rescore
  34. 2026-06-18 17:52 UTCEPSS rescore
  35. 2026-06-18 17:52 UTCEPSS rescore
  36. 2026-06-17 17:52 UTCEPSS rescore
  37. 2026-06-16 17:52 UTCEPSS rescore
  38. 2026-06-16 17:52 UTCEPSS rescore
  39. 2026-06-14 23:18 UTCMITRE cvelistV5
  40. 2026-06-14 23:17 UTCEPSS rescore
  41. 2026-06-13 23:00 UTCEPSS rescore
  42. 2026-06-12 23:11 UTCEPSS rescore
  43. 2026-06-11 14:00 UTCEPSS rescore
  44. 2026-06-10 22:18 UTCEPSS rescore
  45. 2026-06-10 13:22 UTCEPSS rescore
  46. 2026-06-08 14:16 UTCEPSS rescore
  47. 2026-06-08 14:16 UTCEPSS rescore
  48. 2026-06-07 15:24 UTCEPSS rescore
  49. 2026-06-06 13:47 UTCEPSS rescore
  50. 2026-06-06 13:47 UTCEPSS rescore
  51. 2026-06-05 22:46 UTCEPSS rescore
  52. 2026-06-05 22:46 UTCEPSS rescore
  53. 2026-06-05 06:10 UTCEPSS rescore
  54. 2026-06-05 06:10 UTCEPSS rescore
  55. 2026-06-04 13:12 UTCEPSS rescore
  56. 2026-06-04 13:12 UTCEPSS rescore
  57. 2026-06-02 20:12 UTCEPSS rescore
  58. 2026-06-02 15:32 UTCOSV refresh
  59. 2026-06-01 13:51 UTCEPSS rescore
  60. 2026-06-01 13:51 UTCEPSS rescore
  61. 2026-05-31 22:30 UTCEPSS rescore
  62. 2026-05-31 22:30 UTCEPSS rescore
  63. 2026-05-31 00:16 UTCEPSS rescore
  64. 2026-05-29 13:44 UTCEPSS rescore
  65. 2026-05-28 13:44 UTCEPSS rescore
  66. 2026-05-28 13:44 UTCEPSS rescore
  67. 2026-05-28 13:44 UTCEPSS rescore
  68. 2026-05-28 13:44 UTCEPSS rescore
  69. 2026-05-27 13:40 UTCEPSS rescore
  70. 2026-05-27 13:40 UTCEPSS rescore
  71. 2026-05-27 13:40 UTCEPSS rescore
  72. 2026-05-27 13:40 UTCEPSS rescore
  73. 2026-05-26 13:43 UTCEPSS rescore
  74. 2026-05-26 13:43 UTCEPSS rescore
  75. 2026-05-26 13:43 UTCEPSS rescore

Related CVEs(same product + same vendor)

Frequently asked(5)

What is CVE-2025-40300?
CVE-2025-40300 is a medium vulnerability published on September 11, 2025. In the Linux kernel, the following vulnerability has been resolved: x86/vmscape: Add conditional IBPB mitigation VMSCAPE is a vulnerability that exploits insufficient branch predictor isolation between a guest and a userspace hypervisor (like QEMU). Existing mitigations already protect kernel/KVM…
When was CVE-2025-40300 disclosed?
CVE-2025-40300 was first published in the National Vulnerability Database on September 11, 2025, with the most recent update on July 14, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-40300 actively exploited?
CVE-2025-40300 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 25.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2025-40300?
CVE-2025-40300 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2025-40300?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-40300, 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.

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