Vulnerability-Lookup

CVE-2026-64283 (GCVE-0-2026-64283)

Vulnerability from cvelistv5 – Published: 2026-07-25 08:49 – Updated: 2026-11-06 16:34

Title

KVM: guest_memfd: Treat memslot binding offset+size as unsigned values

Summary

In the Linux kernel, the following vulnerability has been resolved: KVM: guest_memfd: Treat memslot binding offset+size as unsigned values When binding a memslot to a guest_memfd file, treat the offset and size as unsigned values to fix a bug where the sum of the two can result in a false negative when checking for overflow against the size of the file. Passing unsigned values also avoids relying on somewhat obscure checks in other flows for safety, and tracks the offset and size as they are intended to be tracked, as unsigned values. On 64-bit kernels, the number of pages a memslot contains and thus the size (and offset) of its guest_memfd binding are unsigned 64-bit values. Taking the offset+size as an loff_t instead of a uoff_t inadvertently converts the unsigned value to a signed value if the offset and/or size is massive. Locally storing the offset and size as signed values is benign in and of itself (though even that is *extremely* difficult to discern), but operating on their sum is not. For the offset, KVM explicitly checks against a negative value, which might seem like a bug as KVM could incorrectly reject a legitimate binding, but that's not actually the case as KVM_CREATE_GUEST_MEMFD takes a signed value for its size, i.e. a would-be-negative offset is also greater than the maximum possible size of any guest_memfd file. Regarding the size, while KVM lacks an explicit check for a negative value, i.e. seemingly has a flawed overflow check, KVM restricts the number of pages in a single memslot to the largest positive signed 32-bit value: if (id < KVM_USER_MEM_SLOTS && (mem->memory_size >> PAGE_SHIFT) > KVM_MEM_MAX_NR_PAGES) return -EINVAL; and so that maximum "size" will ever be is 0x7fffffff000. The sum of the two is, however, problematic. While the size is restricted by KVM's memslot logic, the offset is not, i.e. the offset is completely unchecked until the "offset + size > i_size_read(inode)" check. If the offset is the (nearly) largest possible _positive_ value, then adding size to the offset can result in a signed, negative 64-bit value. When compared against the size of the file (guaranteed to be positive), the negative sum is always smaller, and KVM incorrectly allows the absurd offset. Opportunistically add missing includes in kvm_mm.h (instead of relying on its parents).

Severity

No CVSS data available.

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-11-06 16:33 UTC

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 6639 records in the last 180 days details

References

4 references

URL	Tags
https://git.kernel.org/stable/c/e4683654881f3303a…
https://git.kernel.org/stable/c/3f9c0fdefa0431ad7…
https://git.kernel.org/stable/c/f3a98d5881b9bd480…
https://git.kernel.org/stable/c/eba85fee7fc6cf28f…

Impacted products

2 products

Vendor	Product	Version	CPE status
Linux	Linux	Affected: a7800aa80ea4d5356b8474c2302812e9d4926fa6 , < e4683654881f3303ab286e45df6f91c0675d867c (git) Affected: a7800aa80ea4d5356b8474c2302812e9d4926fa6 , < 3f9c0fdefa0431ad7a5528d76b9cdad912500bdf (git) Affected: a7800aa80ea4d5356b8474c2302812e9d4926fa6 , < f3a98d5881b9bd4807f49156143565f6aabcef1e (git) Affected: a7800aa80ea4d5356b8474c2302812e9d4926fa6 , < eba85fee7fc6cf28fec38a5bf3c378bef9a79ca6 (git)	guessed
Linux	Linux	Affected: 6.8 Unaffected: 0 , < 6.8 (semver) Unaffected: 6.12.114 , ≤ 6.12.* (semver) Unaffected: 6.18.57 , ≤ 6.18.* (semver) Unaffected: 7.1.4 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)	guessed

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                  "lessThan": "eba85fee7fc6cf28fec38a5bf3c378bef9a79ca6",
                  "status": "affected",
                  "version": "a7800aa80ea4d5356b8474c2302812e9d4926fa6",
                  "versionType": "git"
                }
              ]
            },
            {
              "defaultStatus": "affected",
              "product": "Linux",
              "programFiles": [
                "virt/kvm/guest_memfd.c",
                "virt/kvm/kvm_mm.h"
              ],
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "vendor": "Linux",
              "versions": [
                {
                  "status": "affected",
                  "version": "6.8"
                },
                {
                  "lessThan": "6.8",
                  "status": "unaffected",
                  "version": "0",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "6.12.*",
                  "status": "unaffected",
                  "version": "6.12.114",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "6.18.*",
                  "status": "unaffected",
                  "version": "6.18.57",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "7.1.*",
                  "status": "unaffected",
                  "version": "7.1.4",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "*",
                  "status": "unaffected",
                  "version": "7.2",
                  "versionType": "original_commit_for_fix"
                }
              ]
            }
          ],
          "cpeApplicability": [
            {
              "nodes": [
                {
                  "cpeMatch": [
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "6.12.114",
                      "versionStartIncluding": "6.8",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "6.18.57",
                      "versionStartIncluding": "6.8",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "7.1.4",
                      "versionStartIncluding": "6.8",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "7.2",
                      "versionStartIncluding": "6.8",
                      "vulnerable": true
                    }
                  ],
                  "negate": false,
                  "operator": "OR"
                }
              ]
            }
          ],
          "descriptions": [
            {
              "lang": "en",
              "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: guest_memfd: Treat memslot binding offset+size as unsigned values\n\nWhen binding a memslot to a guest_memfd file, treat the offset and size as\nunsigned values to fix a bug where the sum of the two can result in a false\nnegative when checking for overflow against the size of the file.  Passing\nunsigned values also avoids relying on somewhat obscure checks in other\nflows for safety, and tracks the offset and size as they are intended to be\ntracked, as unsigned values.\n\nOn 64-bit kernels, the number of pages a memslot contains and thus the size\n(and offset) of its guest_memfd binding are unsigned 64-bit values.  Taking\nthe offset+size as an loff_t instead of a uoff_t inadvertently converts\nthe unsigned value to a signed value if the offset and/or size is massive.\n\nLocally storing the offset and size as signed values is benign in and of\nitself (though even that is *extremely* difficult to discern), but\noperating on their sum is not.\n\nFor the offset, KVM explicitly checks against a negative value, which might\nseem like a bug as KVM could incorrectly reject a legitimate binding, but\nthat\u0027s not actually the case as KVM_CREATE_GUEST_MEMFD takes a signed value\nfor its size, i.e. a would-be-negative offset is also greater than the\nmaximum possible size of any guest_memfd file.\n\nRegarding the size, while KVM lacks an explicit check for a negative value,\ni.e. seemingly has a flawed overflow check, KVM restricts the number of\npages in a single memslot to the largest positive signed 32-bit value:\n\n        if (id \u003c KVM_USER_MEM_SLOTS \u0026\u0026\n            (mem-\u003ememory_size \u003e\u003e PAGE_SHIFT) \u003e KVM_MEM_MAX_NR_PAGES)\n                return -EINVAL;\n\nand so that maximum \"size\" will ever be is 0x7fffffff000.\n\nThe sum of the two is, however, problematic.  While the size is restricted\nby KVM\u0027s memslot logic, the offset is not, i.e. the offset is completely\nunchecked until the \"offset + size \u003e i_size_read(inode)\" check.  If the\noffset is the (nearly) largest possible _positive_ value, then adding size\nto the offset can result in a signed, negative 64-bit value.  When compared\nagainst the size of the file (guaranteed to be positive), the negative sum\nis always smaller, and KVM incorrectly allows the absurd offset.\n\nOpportunistically add missing includes in kvm_mm.h (instead of relying on\nits parents)."
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-10-21T12:43:13.426Z",
            "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "shortName": "Linux"
          },
          "references": [
            {
              "url": "https://git.kernel.org/stable/c/e4683654881f3303ab286e45df6f91c0675d867c"
            },
            {
              "url": "https://git.kernel.org/stable/c/3f9c0fdefa0431ad7a5528d76b9cdad912500bdf"
            },
            {
              "url": "https://git.kernel.org/stable/c/f3a98d5881b9bd4807f49156143565f6aabcef1e"
            },
            {
              "url": "https://git.kernel.org/stable/c/eba85fee7fc6cf28fec38a5bf3c378bef9a79ca6"
            }
          ],
          "title": "KVM: guest_memfd: Treat memslot binding offset+size as unsigned values",
          "x_generator": {
            "engine": "bippy-1.2.0"
          }
        }
      },
      "cveMetadata": {
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "assignerShortName": "Linux",
        "cveId": "CVE-2026-64283",
        "datePublished": "2026-07-25T08:49:25.642Z",
        "dateReserved": "2026-07-19T15:36:31.777Z",
        "dateUpdated": "2026-11-06T16:34:32.476Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}

GHSA-64FQ-X7R6-WC9G

Vulnerability from github – Published: 2026-07-25 12:31 – Updated: 2026-10-21 15:40

Details

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

KVM: guest_memfd: Treat memslot binding offset+size as unsigned values

When binding a memslot to a guest_memfd file, treat the offset and size as unsigned values to fix a bug where the sum of the two can result in a false negative when checking for overflow against the size of the file. Passing unsigned values also avoids relying on somewhat obscure checks in other flows for safety, and tracks the offset and size as they are intended to be tracked, as unsigned values.

On 64-bit kernels, the number of pages a memslot contains and thus the size (and offset) of its guest_memfd binding are unsigned 64-bit values. Taking the offset+size as an loff_t instead of a uoff_t inadvertently converts the unsigned value to a signed value if the offset and/or size is massive.

Locally storing the offset and size as signed values is benign in and of itself (though even that is extremely difficult to discern), but operating on their sum is not.

For the offset, KVM explicitly checks against a negative value, which might seem like a bug as KVM could incorrectly reject a legitimate binding, but that's not actually the case as KVM_CREATE_GUEST_MEMFD takes a signed value for its size, i.e. a would-be-negative offset is also greater than the maximum possible size of any guest_memfd file.

Regarding the size, while KVM lacks an explicit check for a negative value, i.e. seemingly has a flawed overflow check, KVM restricts the number of pages in a single memslot to the largest positive signed 32-bit value:

    if (id < KVM_USER_MEM_SLOTS &&
        (mem->memory_size >> PAGE_SHIFT) > KVM_MEM_MAX_NR_PAGES)
            return -EINVAL;

and so that maximum "size" will ever be is 0x7fffffff000.

The sum of the two is, however, problematic. While the size is restricted by KVM's memslot logic, the offset is not, i.e. the offset is completely unchecked until the "offset + size > i_size_read(inode)" check. If the offset is the (nearly) largest possible positive value, then adding size to the offset can result in a signed, negative 64-bit value. When compared against the size of the file (guaranteed to be positive), the negative sum is always smaller, and KVM incorrectly allows the absurd offset.

Opportunistically add missing includes in kvm_mm.h (instead of relying on its parents).

Severity

7.0 (High)


                  
                    CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-64283"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-190"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-25T10:17:08Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: guest_memfd: Treat memslot binding offset+size as unsigned values\n\nWhen binding a memslot to a guest_memfd file, treat the offset and size as\nunsigned values to fix a bug where the sum of the two can result in a false\nnegative when checking for overflow against the size of the file.  Passing\nunsigned values also avoids relying on somewhat obscure checks in other\nflows for safety, and tracks the offset and size as they are intended to be\ntracked, as unsigned values.\n\nOn 64-bit kernels, the number of pages a memslot contains and thus the size\n(and offset) of its guest_memfd binding are unsigned 64-bit values.  Taking\nthe offset+size as an loff_t instead of a uoff_t inadvertently converts\nthe unsigned value to a signed value if the offset and/or size is massive.\n\nLocally storing the offset and size as signed values is benign in and of\nitself (though even that is *extremely* difficult to discern), but\noperating on their sum is not.\n\nFor the offset, KVM explicitly checks against a negative value, which might\nseem like a bug as KVM could incorrectly reject a legitimate binding, but\nthat\u0027s not actually the case as KVM_CREATE_GUEST_MEMFD takes a signed value\nfor its size, i.e. a would-be-negative offset is also greater than the\nmaximum possible size of any guest_memfd file.\n\nRegarding the size, while KVM lacks an explicit check for a negative value,\ni.e. seemingly has a flawed overflow check, KVM restricts the number of\npages in a single memslot to the largest positive signed 32-bit value:\n\n        if (id \u003c KVM_USER_MEM_SLOTS \u0026\u0026\n            (mem-\u003ememory_size \u003e\u003e PAGE_SHIFT) \u003e KVM_MEM_MAX_NR_PAGES)\n                return -EINVAL;\n\nand so that maximum \"size\" will ever be is 0x7fffffff000.\n\nThe sum of the two is, however, problematic.  While the size is restricted\nby KVM\u0027s memslot logic, the offset is not, i.e. the offset is completely\nunchecked until the \"offset + size \u003e i_size_read(inode)\" check.  If the\noffset is the (nearly) largest possible _positive_ value, then adding size\nto the offset can result in a signed, negative 64-bit value.  When compared\nagainst the size of the file (guaranteed to be positive), the negative sum\nis always smaller, and KVM incorrectly allows the absurd offset.\n\nOpportunistically add missing includes in kvm_mm.h (instead of relying on\nits parents).",
  "id": "GHSA-64fq-x7r6-wc9g",
  "modified": "2026-10-21T15:40:46Z",
  "published": "2026-07-25T12:31:29Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64283"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3f9c0fdefa0431ad7a5528d76b9cdad912500bdf"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e4683654881f3303ab286e45df6f91c0675d867c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/eba85fee7fc6cf28fec38a5bf3c378bef9a79ca6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f3a98d5881b9bd4807f49156143565f6aabcef1e"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

OPENSUSE-SU-2026:11476-1

Vulnerability from csaf_opensuse - Published: 2026-08-09 00:00 - Updated: 2026-09-26 08:35

Summary

kernel-devel-7.1.7-1.1 on GA media

Severity

Moderate

Scope

351 vulnerabilities in this advisory, including CVE-2026-64283.

CVE-2026-64283

5.5 (Medium)


                
                  CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Recommended: 16 products

Open the full advisory

OPENSUSE-SU-2026:21910-1

Vulnerability from csaf_opensuse - Published: 2026-09-22 15:26 - Updated: 2026-11-03 21:54

Summary

Security update for the Linux Kernel

Severity

Important

Scope

885 vulnerabilities in this advisory, including CVE-2026-64283.

CVE-2026-64283

5.5 (Medium)


                
                  CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Recommended: 136 products

Open the full advisory

SUSE-SU-2026:23881-1

Vulnerability from csaf_suse - Published: 2026-09-22 13:18 - Updated: 2026-11-03 21:47

Summary

Security update for the Linux Kernel

Severity

Important

Scope

885 vulnerabilities in this advisory, including CVE-2026-64283.

CVE-2026-64283

5.5 (Medium)


                
                  CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Recommended: 8 products

Open the full advisory

SUSE-SU-2026:23887-1

Vulnerability from csaf_suse - Published: 2026-09-22 14:23 - Updated: 2026-11-03 21:47

Summary

Security update for the Linux Kernel

Severity

Important

Scope

885 vulnerabilities in this advisory, including CVE-2026-64283.

CVE-2026-64283

5.5 (Medium)


                
                  CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Recommended: 28 products

Open the full advisory

SUSE-SU-2026:23897-1

Vulnerability from csaf_suse - Published: 2026-09-22 13:58 - Updated: 2026-11-03 21:47

Summary

Security update for the Linux Kernel

Severity

Important

Scope

885 vulnerabilities in this advisory, including CVE-2026-64283.

CVE-2026-64283

5.5 (Medium)


                
                  CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Recommended: 9 products

Open the full advisory

SUSE-SU-2026:23902-1

Vulnerability from csaf_suse - Published: 2026-09-22 14:23 - Updated: 2026-11-03 21:47

Summary

Security update for the Linux Kernel

Severity

Important

Scope

885 vulnerabilities in this advisory, including CVE-2026-64283.

CVE-2026-64283

5.5 (Medium)


                
                  CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Recommended: 114 products

Open the full advisory

SUSE-SU-2026:24181-1

Vulnerability from csaf_suse - Published: 2026-10-12 15:51 - Updated: 2026-10-20 09:49

Summary

Security update for the Linux Kernel

Severity

Important

Scope

473 vulnerabilities in this advisory, including CVE-2026-64283.

CVE-2026-64283

5.5 (Medium)


                
                  CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Recommended: 17 products

Open the full advisory

SUSE-SU-2026:24182-1

Vulnerability from csaf_suse - Published: 2026-10-12 14:42 - Updated: 2026-10-20 09:49

Summary

Security update for the Linux Kernel

Severity

Important

Scope

479 vulnerabilities in this advisory, including CVE-2026-64283.

CVE-2026-64283

5.5 (Medium)


                
                  CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Recommended: 20 products

Open the full advisory

SUSE-SU-2026:24315-1

Vulnerability from csaf_suse - Published: 2026-10-12 16:13 - Updated: 2026-10-26 19:20

Summary

Security update for the Linux Kernel

Severity

Important

Scope

473 vulnerabilities in this advisory, including CVE-2026-64283.

CVE-2026-64283

5.5 (Medium)


                
                  CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Recommended: 11 products

Open the full advisory

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.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

Order JSON

How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

Publication & reservation Sightings KEV catalogs Other timestamps

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

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CVE-2026-64283 (GCVE-0-2026-64283)

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