ubuntu-cve-2026-41991
Vulnerability from osv_ubuntu
Published
2026-06-29 12:16
Modified
2026-07-06 18:39
Summary
Details

GNU gzip contains a vulnerability in the gzexe utility related to insecure temporary file handling. When the mktemp utility is not available in the user’s PATH, gzexe falls back to constructing a temporary file path based solely on the process ID (PID). This predictable filename is created without exclusive access or existence checks. A local attacker can pre‑create the predicted temporary file path as a symbolic link pointing to an arbitrary file writable by the victim. When gzexe runs, it follows the symlink and overwrites the target file, resulting in a time‑of‑check to time‑of‑use (TOCTOU) condition that allows arbitrary file overwrite. This issue has been fixed in the commit 4e6f8b24ab823146ab8776f0b7fe486ab34d4269

Severity
2.0 (Low)
CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
4.7 (Medium)
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "gzip",
            "binary_version": "1.6-3ubuntu1+esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:14.04:LTS",
        "name": "gzip",
        "purl": "pkg:deb/ubuntu/gzip@1.6-3ubuntu1+esm1?arch=source\u0026distro=esm-infra-legacy/trusty"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.6-2ubuntu1",
        "1.6-3ubuntu1",
        "1.6-3ubuntu1+esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "gzip",
            "binary_version": "1.6-4ubuntu1+esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:16.04:LTS",
        "name": "gzip",
        "purl": "pkg:deb/ubuntu/gzip@1.6-4ubuntu1+esm1?arch=source\u0026distro=esm-infra/xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.6-4ubuntu1",
        "1.6-4ubuntu1+esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "gzip",
            "binary_version": "1.6-5ubuntu1.2"
          },
          {
            "binary_name": "gzip-win32",
            "binary_version": "1.6-5ubuntu1.2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:18.04:LTS",
        "name": "gzip",
        "purl": "pkg:deb/ubuntu/gzip@1.6-5ubuntu1.2?arch=source\u0026distro=bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.6-5ubuntu1",
        "1.6-5ubuntu1.1",
        "1.6-5ubuntu1.2"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "gzip",
            "binary_version": "1.10-0ubuntu4.1"
          },
          {
            "binary_name": "gzip-win32",
            "binary_version": "1.10-0ubuntu4.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "gzip",
        "purl": "pkg:deb/ubuntu/gzip@1.10-0ubuntu4.1?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.10-0ubuntu3",
        "1.10-0ubuntu4",
        "1.10-0ubuntu4.1"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "gzip",
            "binary_version": "1.10-4ubuntu4.2"
          },
          {
            "binary_name": "gzip-win32",
            "binary_version": "1.10-4ubuntu4.2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "gzip",
        "purl": "pkg:deb/ubuntu/gzip@1.10-4ubuntu4.2?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.10-4ubuntu4.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.10-4ubuntu1",
        "1.10-4ubuntu2",
        "1.10-4ubuntu3",
        "1.10-4ubuntu4",
        "1.10-4ubuntu4.1"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "gzip",
            "binary_version": "1.12-1ubuntu3.2"
          },
          {
            "binary_name": "gzip-win32",
            "binary_version": "1.12-1ubuntu3.2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "gzip",
        "purl": "pkg:deb/ubuntu/gzip@1.12-1ubuntu3.2?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.12-1ubuntu3.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.12-1ubuntu1",
        "1.12-1ubuntu2",
        "1.12-1ubuntu3",
        "1.12-1ubuntu3.1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "gzip",
            "binary_version": "1.13-1ubuntu4"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "gzip",
        "purl": "pkg:deb/ubuntu/gzip@1.13-1ubuntu4?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.13-1ubuntu3",
        "1.13-1ubuntu4"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "gzip",
            "binary_version": "1.14-1~exp2ubuntu1.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "gzip",
        "purl": "pkg:deb/ubuntu/gzip@1.14-1~exp2ubuntu1.1?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.14-1~exp2ubuntu1.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.13-1ubuntu4",
        "1.13-1ubuntu5",
        "1.14-1~exp2ubuntu1"
      ]
    }
  ],
  "aliases": [],
  "details": "GNU gzip contains a vulnerability in the gzexe utility related to insecure temporary file handling. When the mktemp utility is not available in the user\u2019s PATH, gzexe falls back to constructing a temporary file path based solely on the process ID (PID). This predictable filename is created without exclusive access or existence checks. A local attacker can pre\u2011create the predicted temporary file path as a symbolic link pointing to an arbitrary file writable by the victim. When gzexe runs, it follows the symlink and overwrites the target file, resulting in a time\u2011of\u2011check to time\u2011of\u2011use (TOCTOU) condition that allows arbitrary file overwrite. This issue has been fixed in the commit 4e6f8b24ab823146ab8776f0b7fe486ab34d4269",
  "id": "UBUNTU-CVE-2026-41991",
  "modified": "2026-07-06T18:39:30Z",
  "published": "2026-06-29T12:16:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-41991"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-41991"
    },
    {
      "type": "REPORT",
      "url": "https://cert.pl/en/posts/2026/04/CVE-2026-41991/"
    },
    {
      "type": "REPORT",
      "url": "https://www.gnu.org/software/gzip/"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-8512-1"
    }
  ],
  "related": [
    "USN-8512-1"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    },
    {
      "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-41991"
  ]
}



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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.

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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.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.