Vulnerability-Lookup

GHSA-R5C7-VPW8-XF4V

Vulnerability from github – Published: 2026-09-16 15:31 – Updated: 2026-09-16 15:31

Details

When the sandbox virtualizes a file it copies the original security descriptor, but the driver opened the virtualization target object with GENERIC_WRITE and FILE_WRITE_ATTRIBUTES only, omitting WRITE_DAC. Every attempt to apply the original DACL therefore failed, and the failure was discarded silently, leaving virtualized copies of sensitive files with permissive permissions. Because the IRP_MJ_CREATE callback additionally did not strip WRITE_DAC for sensitive directories, a sandboxed process could rewrite the security descriptor of a virtualized object, read the virtualized copy of the SAM database, extract local NTLM password hashes and execute code as SYSTEM.

The absence of an IRP_MJ_SET_SECURITY callback in the driver's operation registration table is a related defense-in-depth gap, but it is not the control that prevents this attack.

Severity

8.8 (High)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-82964"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-281"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-16T15:17:55Z",
    "severity": "HIGH"
  },
  "details": "Improper preservation of permissions in the Avast sandbox minifilter driver (aswSnx.sys) on Windows allows a local, low-privileged attacker executing inside the sandbox to escape file isolation and escalate to SYSTEM.\n\n\n\nWhen the sandbox virtualizes a file it copies the original security descriptor, but the driver opened the virtualization target object with GENERIC_WRITE and FILE_WRITE_ATTRIBUTES only, omitting WRITE_DAC. Every attempt to apply the original DACL therefore failed, and the failure was discarded silently, leaving virtualized copies of sensitive files with permissive permissions. Because the IRP_MJ_CREATE callback additionally did not strip WRITE_DAC for sensitive directories, a sandboxed process could rewrite the security descriptor of a virtualized object, read the virtualized copy of the SAM database, extract local NTLM password hashes and execute code as SYSTEM.\n\n\n\nThe absence of an IRP_MJ_SET_SECURITY callback in the driver\u0027s operation registration table is a related defense-in-depth gap, but it is not the control that prevents this attack.",
  "id": "GHSA-r5c7-vpw8-xf4v",
  "modified": "2026-09-16T15:31:13Z",
  "published": "2026-09-16T15:31:13Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-82964"
    },
    {
      "type": "WEB",
      "url": "https://github.com/MSNightmare/PrettyPrague"
    },
    {
      "type": "WEB",
      "url": "https://support.avast.com/en-us/article/Update-Antivirus"
    },
    {
      "type": "WEB",
      "url": "https://support.avg.com/SupportArticleView?l=en\u0026urlname=Update-AVG-Antivirus"
    },
    {
      "type": "WEB",
      "url": "https://support.norton.com/sp/en/us/home/current/solutions/v20240108175512167"
    },
    {
      "type": "WEB",
      "url": "https://www.gendigital.com/us/en/contact-us/security-advisories"
    },
    {
      "type": "WEB",
      "url": "https://x.com/msnightmare2000/status/2094106041046765752"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-82964 (GCVE-0-2026-82964)

Vulnerability from cvelistv5 – Published: 2026-09-16 14:01 – Updated: 2026-09-17 18:42

Title

Avast sandbox privilege escalation via unpreserved DACLs on virtualized files in aswSnx.sys

Summary

Improper preservation of permissions in the Avast sandbox minifilter driver (aswSnx.sys) on Windows allows a local, low-privileged attacker executing inside the sandbox to escape file isolation and escalate to SYSTEM. When the sandbox virtualizes a file it copies the original security descriptor, but the driver opened the virtualization target object with GENERIC_WRITE and FILE_WRITE_ATTRIBUTES only, omitting WRITE_DAC. Every attempt to apply the original DACL therefore failed, and the failure was discarded silently, leaving virtualized copies of sensitive files with permissive permissions. Because the IRP_MJ_CREATE callback additionally did not strip WRITE_DAC for sensitive directories, a sandboxed process could rewrite the security descriptor of a virtualized object, read the virtualized copy of the SAM database, extract local NTLM password hashes and execute code as SYSTEM. The absence of an IRP_MJ_SET_SECURITY callback in the driver's operation registration table is a related defense-in-depth gap, but it is not the control that prevents this attack.

Severity

8.8 (High)


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

SSVC

Exploitation: poc Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-17 18:41 UTC

CWE

CWE-281 - Improper Preservation of Permissions
CWE-653 - Improper Isolation or Compartmentalization
CWE-862 - Missing Authorization

Assigner

GEN CNA under the mitre root

CNA scorecard B 75/100 over 24 records in the last 180 days details

References

6 references

URL	Tags
https://www.gendigital.com/us/en/contact-us/secur…	vendor-advisory
https://support.avast.com/en-us/article/Update-An…	patch
https://support.avg.com/SupportArticleView?l=en&u…	patch
https://support.norton.com/sp/en/us/home/current/…	patch
https://github.com/MSNightmare/PrettyPrague	exploit
https://x.com/msnightmare2000/status/209410604104…

Impacted products

3 products

Vendor	Product	Version
Gen Digital	Avast Free Antivirus, Avast One, Avast Premium Security, Avast Ultimate, Avast Business Security	Affected: 0 , < 26.8 (custom)
Gen Digital	AVG Antivirus Free, AVG Internet Security, AVG Ultimate	Affected: 0 , < 26.8 (custom)
Gen Digital	Norton Antivirus Plus, Norton 360 Standard, Norton 360 Deluxe, Norton 360 Advanced	Affected: 0 , < 26.8 (custom)

Credits

MSNightmare, independent security researcher

Show details on NVD website

JSON

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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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