CVE-2026-64104 (GCVE-0-2026-64104)

Vulnerability from cvelistv5 – Published: 2026-07-19 15:40 – Updated: 2026-08-05 12:39
VLAI
Title
virt: sev-guest: Explicitly leak pages in unknown state
Summary
In the Linux kernel, the following vulnerability has been resolved: virt: sev-guest: Explicitly leak pages in unknown state When set_memory_{encrypted,decrypted}() fail, the user cannot know at which point the function failed, meaning that the pages are left in an unknown state from the point of view of the caller. Since the pages may be left in an unencrypted state, they are not suitable for general use, and cannot be returned safely to the buddy allocator. Avoid the issue by never freeing the pages, and then do the proper accounting by calling snp_leak_pages().
Severity
8.7 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 3e385c0d6ce88ac9916dcf84267bd5855d830748 , < bee400ad4f4259c9c0758e4f1960a1eed6f6f9f0 (git)
Affected: 3e385c0d6ce88ac9916dcf84267bd5855d830748 , < 3d0cd0065deeb054b4b29236432e851806b7cc81 (git)
Affected: 3e385c0d6ce88ac9916dcf84267bd5855d830748 , < fd948c3f96b18ff9ba7d3e8eae13d196593e1aaf (git)
Affected: 0b16521f95c875e79d657cb8d6911c15080dbb80 (git)
Affected: 6.13.8 , < 6.14 (semver)
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Linux Linux Affected: 6.14
Unaffected: 0 , < 6.14 (semver)
Unaffected: 6.18.34 , ≤ 6.18.* (semver)
Unaffected: 7.0.11 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/virt/coco/sev-guest/sev-guest.c"
          ],
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          "vendor": "Linux",
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              "operator": "OR"
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      "descriptions": [
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvirt: sev-guest: Explicitly leak pages in unknown state\n\nWhen set_memory_{encrypted,decrypted}() fail, the user cannot know at which\npoint the function failed, meaning that the pages are left in an unknown state\nfrom the point of view of the caller.\n\nSince the pages may be left in an unencrypted state, they are not suitable for\ngeneral use, and cannot be returned safely to the buddy allocator. Avoid the\nissue by never freeing the pages, and then do the proper accounting by calling\nsnp_leak_pages()."
        }
      ],
      "metrics": [
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L",
            "version": "3.1"
          },
          "scenarios": [
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              "lang": "en",
              "value": "AV:L - The bug is in `get_ext_report()` and is reached only via `SNP_GET_EXT_REPORT` ioctl on `/dev/sev-guest` (or the kernel-internal configfs-TSM path), which requires local access inside an AMD SEV-SNP confidential guest VM.\nAC:L - A local caller can repeatedly issue `SNP_GET_EXT_REPORT` with a non-zero, page-aligned `certs_len` to drive allocation and `set_memory_decrypted()`/`set_memory_encrypted()`; on failure after `snp_set_memory_shared()` has already run, the pre-fix path incorrectly returned those pages to the buddy allocator.\nPR:L - Exploitation requires opening `/dev/sev-guest` and issuing the ioctl; in typical confidential-VM deployments attestation is performed by unprivileged workloads, and the ioctl path does not require real root in the init namespace.\nUI:N - Triggering the vulnerable cleanup requires only programmatic ioctl calls to obtain an extended attestation report; no victim user action such as mounting a filesystem or opening a file is needed.\nS:C - Returning pages that may remain in shared/unencrypted RMP state to the buddy allocator breaks the SEV-SNP guest-to-hypervisor memory confidentiality boundary, allowing a malicious or compromised hypervisor to read (and tamper with) guest kernel memory later allocated on those pages.\nC:H - Pages can be left hypervisor-visible while re-entering the general kernel page pool, enabling disclosure of arbitrary subsequent guest kernel memory contents (keys, crypto material, process data) to the untrusted host.\nI:H - Shared RMP pages reused by the kernel can be modified by the hypervisor before the guest reads them, providing a write primitive against guest kernel memory that can undermine integrity of kernel data structures and potentially enable further compromise.\nA:L - The flaw does not directly panic the kernel, but repeated triggering of the error path can stress page accounting and, in worst cases, contribute to allocator instability; availability impact is limited rather than a reliable crash."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:39:15.778Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/bee400ad4f4259c9c0758e4f1960a1eed6f6f9f0"
        },
        {
          "url": "https://git.kernel.org/stable/c/3d0cd0065deeb054b4b29236432e851806b7cc81"
        },
        {
          "url": "https://git.kernel.org/stable/c/fd948c3f96b18ff9ba7d3e8eae13d196593e1aaf"
        }
      ],
      "title": "virt: sev-guest: Explicitly leak pages in unknown state",
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        "engine": "bippy-1.2.0"
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    }
  },
  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64104",
    "datePublished": "2026-07-19T15:40:07.994Z",
    "dateReserved": "2026-07-19T07:54:57.034Z",
    "dateUpdated": "2026-08-05T12:39:15.778Z",
    "state": "PUBLISHED"
  },
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    "redhat_vex": {
      "aggregate_severity": "None",
      "current_release_date": "2026-07-21T08:04:36+00:00",
      "cve": "CVE-2026-64104",
      "id": "CVE-2026-64104",
      "initial_release_date": "2026-07-19T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: virt: sev-guest: Explicitly leak pages in unknown state",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64104.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-08-05T00:33:28Z",
      "cve": "CVE-2026-64104",
      "id": "CVE-2026-64104",
      "initial_release_date": "2026-07-21T12:59:37Z",
      "product_status:known_not_affected": "296",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-64104",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-64104.json",
      "version": "3"
    }
  }
}



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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

Author Source Type Date Other

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.