CVE-2023-53996 (GCVE-0-2023-53996)

Vulnerability from cvelistv5 – Published: 2025-12-24 10:55 – Updated: 2026-08-05 09:16
VLAI
Title
x86/sev: Make enc_dec_hypercall() accept a size instead of npages
Summary
In the Linux kernel, the following vulnerability has been resolved: x86/sev: Make enc_dec_hypercall() accept a size instead of npages enc_dec_hypercall() accepted a page count instead of a size, which forced its callers to round up. As a result, non-page aligned vaddrs caused pages to be spuriously marked as decrypted via the encryption status hypercall, which in turn caused consistent corruption of pages during live migration. Live migration requires accurate encryption status information to avoid migrating pages from the wrong perspective.
Severity
9.3 (Critical)
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 064ce6c550a0630789978bfec7a13ab2bd1bdcdf , < ba50e7773a99a109a1ea6f753b766a080d3b21cc (git)
Affected: 064ce6c550a0630789978bfec7a13ab2bd1bdcdf , < 6615212d8e131b45bd9705b0d69cc0d2f624666f (git)
Affected: 064ce6c550a0630789978bfec7a13ab2bd1bdcdf , < 8ae7457e71a320867d868f2622d7c643596e4f43 (git)
Affected: 064ce6c550a0630789978bfec7a13ab2bd1bdcdf , < ac3f9c9f1b37edaa7d1a9b908bc79d843955a1a2 (git)
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Linux Linux Affected: 5.16
Unaffected: 0 , < 5.16 (semver)
Unaffected: 6.1.53 , ≤ 6.1.* (semver)
Unaffected: 6.4.16 , ≤ 6.4.* (semver)
Unaffected: 6.5.3 , ≤ 6.5.* (semver)
Unaffected: 6.6 , ≤ * (original_commit_for_fix)
Create a notification for this product.
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{
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    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/x86/include/asm/mem_encrypt.h",
            "arch/x86/kernel/kvm.c",
            "arch/x86/mm/mem_encrypt_amd.c"
          ],
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          "vendor": "Linux",
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          "vendor": "Linux",
          "versions": [
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nx86/sev: Make enc_dec_hypercall() accept a size instead of npages\n\nenc_dec_hypercall() accepted a page count instead of a size, which\nforced its callers to round up. As a result, non-page aligned\nvaddrs caused pages to be spuriously marked as decrypted via the\nencryption status hypercall, which in turn caused consistent\ncorruption of pages during live migration. Live migration requires\naccurate encryption status information to avoid migrating pages\nfrom the wrong perspective."
        }
      ],
      "metrics": [
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            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
          },
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              "value": "AV:L - The defective code is guest `__init` code in `arch/x86/mm/mem_encrypt_amd.c` and the damage is delivered by hypervisor-side memory/migration operations on the same physical host; no network protocol data reaches the vulnerable function. This matches the AV:L scoring of comparable guest-side x86/sev confidential-computing flaws.\nAC:L - The mis-reporting is deterministic \u2014 the percpu variables passed to `early_set_memory_decrypted()` are always non-page-aligned, so the extra page is spuriously declared shared on every SEV guest boot, and the commit explicitly describes \"consistent corruption\" with no race or memory-layout luck involved. The party that triggers the damaging step (live migration) controls it completely.\nPR:N - No privileges of any kind are required inside the guest \u2014 the wrong encryption status is registered during early boot and the corruption lands during a routine, guest-transparent live migration. In the SEV threat model the untrusted hypervisor needs no guest credentials to reach this state.\nUI:N - Live migration is transparent to the guest and requires no action by any guest user; the mis-declaration itself happens automatically at boot.\nS:C - The guest kernel bug corrupts state held by a different security authority \u2014 the hypervisor\u0027s page-encryption-status list \u2014 causing memory protected by the SEV/AMD-SP confidential-computing boundary to be handled by the host as shared. The impact therefore crosses the guest/host CoCo boundary rather than staying within the guest\u0027s own authority.\nC:H - Pages containing guest-private kernel data are declared shared to the untrusted hypervisor, so they are handled outside the SEV-protected migration path (raw-copied across the migration channel rather than PSP-wrapped) and the host treats them as memory it may freely read. Wholesale corruption of kernel percpu pages is also leverageable toward disclosure.\nI:H - The commit documents consistent corruption of entire guest kernel pages during live migration, and the mis-marked private pages are additionally exposed to host writes as \"shared\" memory \u2014 a direct integrity break of guest-private memory.\nA:H - The corrupted pages sit in the kernel percpu region adjacent to `apf_reason`/`steal_time`/`kvm_apic_eoi`; consuming pseudorandom garbage there after migration reliably leads to kernel oops/panic and an unusable guest."
            }
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      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T09:16:33.065Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/ba50e7773a99a109a1ea6f753b766a080d3b21cc"
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          "url": "https://git.kernel.org/stable/c/ac3f9c9f1b37edaa7d1a9b908bc79d843955a1a2"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2023-53996",
    "datePublished": "2025-12-24T10:55:33.402Z",
    "dateReserved": "2025-12-24T10:53:46.176Z",
    "dateUpdated": "2026-08-05T09:16:33.065Z",
    "state": "PUBLISHED"
  },
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      "date": "2026-08-09",
      "epss": "0.00099",
      "percentile": "0.00937"
    },
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-04T19:15:07+00:00",
      "cve": "CVE-2023-53996",
      "id": "CVE-2023-53996",
      "initial_release_date": "2023-01-01T00:00:00+00:00",
      "product_status:fixed": "507",
      "product_status:known_affected": "52",
      "product_status:known_not_affected": "104",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: x86/sev: Make enc_dec_hypercall() accept a size instead of npages",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2023/cve-2023-53996.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-07-25T02:10:20Z",
      "cve": "CVE-2023-53996",
      "id": "CVE-2023-53996",
      "initial_release_date": "2025-12-25T00:58:07Z",
      "product_status:known_affected": "354",
      "product_status:known_not_affected": "231",
      "product_status:recommended": "455",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2023-53996",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2023-53996.json",
      "version": "34"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.