Predictable Temporary File in GNU gzip

{
  "id": "6931e419aa9a13e40f9e848e5dda8336b530c306cdab30fff77a24ec005cf85c",
  "url": "https://osv.dev/vulnerability/CVE-2026-41991",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Predictable Temporary File in GNU gzip",
    "summary": "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",
    "evidence": "osv:CVE-2026-41991",
    "products": [],
    "severity": "low",
    "structured": {
      "id": "CVE-2026-41991",
      "aliases": [
        "CVE-2026-41991"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "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"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://cgit.git.savannah.gnu.org/cgit/gzip.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "4e6f8b24ab823146ab8776f0b7fe486ab34d4269"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "fixed": "4e6f8b24ab823146ab8776f0b7fe486ab34d4269"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-41991.json"
          }
        }
      ],
      "modified": "2026-10-31T10:30:31.576594440Z",
      "provider": "osv",
      "references": [
        "https://cgit.git.savannah.gnu.org/cgit/gzip.git/",
        "https://www.gnu.org/software/gzip/",
        "https://cert.pl/en/posts/2026/04/CVE-2026-41991/",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/41xxx/CVE-2026-41991.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-41991",
        "https://cgit.git.savannah.gnu.org/cgit/gzip.git/commit/?id=4e6f8b24ab823146ab8776f0b7fe486ab34d4269"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-377"
        ],
        "cna_assigner": "CERT-PL",
        "unresolved_ranges": [
          {
            "extracted_events": [
              {
                "range": [
                  {
                    "last_affected": "1.14"
                  }
                ],
                "source": "AFFECTED_FIELD",
                "strategy": "StandardRange"
              }
            ]
          }
        ],
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/41xxx/CVE-2026-41991.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-41991",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 460023,
  "published_at": "2026-06-29T10:15:50.766+00:00"
}