Vulnerability-Lookup

GHSA-PWV5-R8HR-FVGR

Vulnerability from github – Published: 2026-09-08 15:31 – Updated: 2026-09-08 18:31

Details

x86 PV guests can free memory pages while still keeping a stale TLB entry pointing to them. A TLB flush is only issued by Xen (if needed) when the page is re-used. Since it's possible for the page to be scrubbed ahead of the TLB flush, there's a window where a PV guest can modify an already scrubbed page.

Severity

4.3 (Medium)


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

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JSON

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{
  "affected": [],
  "aliases": [
    "CVE-2026-79603"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-664"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-08T13:17:27Z",
    "severity": "MODERATE"
  },
  "details": "x86 PV guests can free memory pages while still keeping a stale TLB entry\npointing to them.  A TLB flush is only issued by Xen (if needed) when the\npage is re-used.  Since it\u0027s possible for the page to be scrubbed ahead of\nthe TLB flush, there\u0027s a window where a PV guest can modify an already\nscrubbed page.",
  "id": "GHSA-pwv5-r8hr-fvgr",
  "modified": "2026-09-08T18:31:48Z",
  "published": "2026-09-08T15:31:54Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-79603"
    },
    {
      "type": "WEB",
      "url": "https://xenbits.xenproject.org/xsa/advisory-511.html"
    },
    {
      "type": "WEB",
      "url": "http://www.openwall.com/lists/oss-security/2026/09/08/8"
    },
    {
      "type": "WEB",
      "url": "http://xenbits.xen.org/xsa/advisory-511.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-79603 (GCVE-0-2026-79603)

Vulnerability from cvelistv5 – Published: 2026-09-08 12:11 – Updated: 2026-09-08 17:08

Title

Unconditionally do TLB flushing ahead of page scrubbing

Summary

Severity

4.3 (Medium)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-08 13:42 UTC

CWE

CWE-664 - Improper Control of a Resource Through its Lifetime

Assigner

XEN mitre root

References

3 references

URL	Tags
https://xenbits.xenproject.org/xsa/advisory-511.html
http://xenbits.xen.org/xsa/advisory-511.html
http://www.openwall.com/lists/oss-security/2026/09/08/8

Impacted products

1 product

Vendor	Product	Version
Xen	Xen	Unknown: consult Xen advisory XSA-511

Date Public

2026-09-08 12:00

Credits

This issue was discovered by Roger Pau Monné of AMD.

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2026-09-08T17:08:33.807Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "url": "http://xenbits.xen.org/xsa/advisory-511.html"
          },
          {
            "url": "http://www.openwall.com/lists/oss-security/2026/09/08/8"
          }
        ],
        "title": "CVE Program Container"
      },
      {
        "metrics": [
          {
            "cvssV3_1": {
              "attackComplexity": "LOW",
              "attackVector": "NETWORK",
              "availabilityImpact": "NONE",
              "baseScore": 4.3,
              "baseSeverity": "MEDIUM",
              "confidentialityImpact": "LOW",
              "integrityImpact": "NONE",
              "privilegesRequired": "LOW",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N",
              "version": "3.1"
            }
          },
          {
            "other": {
              "content": {
                "id": "CVE-2026-79603",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-09-08T13:42:37.092287Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "problemTypes": [
          {
            "descriptions": [
              {
                "cweId": "CWE-664",
                "description": "CWE-664 Improper Control of a Resource Through its Lifetime",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-09-08T13:42:41.424Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unknown",
          "product": "Xen",
          "vendor": "Xen",
          "versions": [
            {
              "status": "unknown",
              "version": "consult Xen advisory XSA-511"
            }
          ]
        }
      ],
      "configurations": [
        {
          "lang": "en",
          "value": "All Xen versions from 4.13 onwards are vulnerable.  Xen versions 4.12 and\nearlier are not vulnerable as they lack the `scrub-domheap` command line\noption.\n\nOnly x86 PV guests can exploit the vulnerability."
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "This issue was discovered by Roger Pau Monn\u00e9 of AMD."
        }
      ],
      "datePublic": "2026-09-08T12:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "x86 PV guests can free memory pages while still keeping a stale TLB entry\npointing to them.  A TLB flush is only issued by Xen (if needed) when the\npage is re-used.  Since it\u0027s possible for the page to be scrubbed ahead of\nthe TLB flush, there\u0027s a window where a PV guest can modify an already\nscrubbed page."
        }
      ],
      "impacts": [
        {
          "descriptions": [
            {
              "lang": "en",
              "value": "Deployments using `xsm=silo scrub-domheap` with the aim of not allowing the\nexchange of information amongst guests are not effective in the presence of\nPV guests."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-08T12:11:21.789Z",
        "orgId": "23aa2041-22e1-471f-9209-9b7396fa234f",
        "shortName": "XEN"
      },
      "references": [
        {
          "url": "https://xenbits.xenproject.org/xsa/advisory-511.html"
        }
      ],
      "title": "Unconditionally do TLB flushing ahead of page scrubbing",
      "workarounds": [
        {
          "lang": "en",
          "value": "There is no known mitigation."
        }
      ]
    }
  },
  "cveMetadata": {
    "assignerOrgId": "23aa2041-22e1-471f-9209-9b7396fa234f",
    "assignerShortName": "XEN",
    "cveId": "CVE-2026-79603",
    "datePublished": "2026-09-08T12:11:21.789Z",
    "dateReserved": "2026-08-25T07:35:05.289Z",
    "dateUpdated": "2026-09-08T17:08:33.807Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

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.

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GHSA-PWV5-R8HR-FVGR

CVE-2026-79603 (GCVE-0-2026-79603)

Tags

Sightings

Nomenclature