ubuntu-cve-2026-48095
Vulnerability from osv_ubuntu
Published
2026-06-05 15:16
Modified
2026-06-11 13:06
Summary
Details

7-Zip is a file archiver with a high compression ratio. Versions 26.00 and prior contain a heap buffer overflow vulnerability caused by an under-allocation in the NTFS compressed stream buffer (GetCuSize shift UB), potentially allowing attackers to cause arbitrary code execution or application crashes. CInStream::GetCuSize() in the NTFS handler computes the compression-unit buffer size as (UInt32)1 << (BlockSizeLog + CompressionUnit), and a crafted image with ClusterSizeLog >= 28 and CompressionUnit == 4 drives the exponent to 32, which is undefined behavior and collapses on x86/x64 so _inBuf is allocated as 1 byte. ReadStream_FALSE then writes up to 256 MB of attacker-controlled data into that 1-byte buffer in 64 KB iterations, and because the CInStream object sits only 304 bytes after _inBuf, its vtable pointer is overwritten and the next dispatched call achieves a vtable hijack. On 32-bit builds the overflow is unconditionally reached; on 64-bit it requires the parallel 8 GB _outBuf allocation to succeed, otherwise failing closed to denial of service. The NTFS handler is enabled by default in stock 7z.dll and, via signature-based fallback matching "NTFS " at offset 3, will open a crafted image regardless of file extension during extraction or testing. Version 26.01 fixes the issue.

Severity
8.8 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "p7zip",
            "binary_version": "9.20.1~dfsg.1-4+deb7u3build0.14.04.1"
          },
          {
            "binary_name": "p7zip-full",
            "binary_version": "9.20.1~dfsg.1-4+deb7u3build0.14.04.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:14.04:LTS",
        "name": "p7zip",
        "purl": "pkg:deb/ubuntu/p7zip@9.20.1~dfsg.1-4+deb7u3build0.14.04.1?arch=source\u0026distro=trusty"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "9.20.1~dfsg.1-4",
        "9.20.1~dfsg.1-4+deb7u1build0.14.04.1",
        "9.20.1~dfsg.1-4+deb7u2build0.14.04.1",
        "9.20.1~dfsg.1-4+deb7u3build0.14.04.1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "p7zip",
            "binary_version": "9.20.1~dfsg.1-4.2ubuntu0.1"
          },
          {
            "binary_name": "p7zip-full",
            "binary_version": "9.20.1~dfsg.1-4.2ubuntu0.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:16.04:LTS",
        "name": "p7zip",
        "purl": "pkg:deb/ubuntu/p7zip@9.20.1~dfsg.1-4.2ubuntu0.1?arch=source\u0026distro=xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "9.20.1~dfsg.1-4.2",
        "9.20.1~dfsg.1-4.2ubuntu0.1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "p7zip",
            "binary_version": "16.02+dfsg-6"
          },
          {
            "binary_name": "p7zip-full",
            "binary_version": "16.02+dfsg-6"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:18.04:LTS",
        "name": "p7zip",
        "purl": "pkg:deb/ubuntu/p7zip@16.02+dfsg-6?arch=source\u0026distro=bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "16.02+dfsg-4",
        "16.02+dfsg-5",
        "16.02+dfsg-6"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "p7zip",
            "binary_version": "16.02+dfsg-7build1"
          },
          {
            "binary_name": "p7zip-full",
            "binary_version": "16.02+dfsg-7build1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "p7zip",
        "purl": "pkg:deb/ubuntu/p7zip@16.02+dfsg-7build1?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "16.02+dfsg-7",
        "16.02+dfsg-7build1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "p7zip",
            "binary_version": "16.02+dfsg-8"
          },
          {
            "binary_name": "p7zip-full",
            "binary_version": "16.02+dfsg-8"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "p7zip",
        "purl": "pkg:deb/ubuntu/p7zip@16.02+dfsg-8?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "16.02+dfsg-8"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "7zip",
            "binary_version": "21.07+dfsg-4ubuntu0.1~esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:22.04:LTS",
        "name": "7zip",
        "purl": "pkg:deb/ubuntu/7zip@21.07+dfsg-4ubuntu0.1~esm1?arch=source\u0026distro=esm-apps/jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "21.03~beta+dfsg-6",
        "21.04~beta+dfsg-1",
        "21.06+dfsg-1",
        "21.07+dfsg-1",
        "21.07+dfsg-2",
        "21.07+dfsg-3",
        "21.07+dfsg-4",
        "21.07+dfsg-4ubuntu0.1~esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "7zip",
            "binary_version": "23.01+dfsg-11ubuntu0.1~esm1"
          },
          {
            "binary_name": "7zip-standalone",
            "binary_version": "23.01+dfsg-11ubuntu0.1~esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:24.04:LTS",
        "name": "7zip",
        "purl": "pkg:deb/ubuntu/7zip@23.01+dfsg-11ubuntu0.1~esm1?arch=source\u0026distro=esm-apps/noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "23.01+dfsg-3",
        "23.01+dfsg-7",
        "23.01+dfsg-8",
        "23.01+dfsg-11",
        "23.01+dfsg-11ubuntu0.1~esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "7zip",
            "binary_version": "25.01+dfsg-2"
          },
          {
            "binary_name": "7zip-standalone",
            "binary_version": "25.01+dfsg-2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "7zip",
        "purl": "pkg:deb/ubuntu/7zip@25.01+dfsg-2?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "24.09+dfsg-7",
        "24.09+dfsg-8",
        "25.00+dfsg-1",
        "25.01+dfsg-1",
        "25.01+dfsg-2"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "7zip",
            "binary_version": "26.00+dfsg-1"
          },
          {
            "binary_name": "7zip-standalone",
            "binary_version": "26.00+dfsg-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "7zip",
        "purl": "pkg:deb/ubuntu/7zip@26.00+dfsg-1?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "25.01+dfsg-2",
        "25.01+dfsg-3",
        "25.01+dfsg-4",
        "25.01+dfsg-5",
        "26.00+dfsg-1"
      ]
    }
  ],
  "aliases": [],
  "details": "7-Zip is a file archiver with a high compression ratio. Versions 26.00 and prior contain a heap buffer overflow vulnerability caused by an under-allocation in the NTFS compressed stream buffer (GetCuSize shift UB), potentially allowing attackers to cause arbitrary code execution or application crashes. CInStream::GetCuSize() in the NTFS handler computes the compression-unit buffer size as (UInt32)1 \u003c\u003c (BlockSizeLog + CompressionUnit), and a crafted image with ClusterSizeLog \u003e= 28 and CompressionUnit == 4 drives the exponent to 32, which is undefined behavior and collapses on x86/x64 so _inBuf is allocated as 1 byte. ReadStream_FALSE then writes up to 256 MB of attacker-controlled data into that 1-byte buffer in 64 KB iterations, and because the CInStream object sits only 304 bytes after _inBuf, its vtable pointer is overwritten and the next dispatched call achieves a vtable hijack. On 32-bit builds the overflow is unconditionally reached; on 64-bit it requires the parallel 8 GB _outBuf allocation to succeed, otherwise failing closed to denial of service. The NTFS handler is enabled by default in stock 7z.dll and, via signature-based fallback matching \"NTFS    \" at offset 3, will open a crafted image regardless of file extension during extraction or testing. Version 26.01 fixes the issue.",
  "id": "UBUNTU-CVE-2026-48095",
  "modified": "2026-06-11T13:06:29Z",
  "published": "2026-06-05T15:16:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-48095"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-48095"
    },
    {
      "type": "REPORT",
      "url": "https://securitylab.github.com/advisories/GHSL-2026-140_7-Zip/"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-48095"
  ]
}



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