MediumFix available

gzip — security advisory

Type: advisorySources: OSVAdvisory ID: DEBIAN-CVE-2026-41991

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

Products: gzip
Affected versions: 1.12-1, 1.12-1.1, 1.12-1.2, 1.13-1, 1.13.56~e549-1~exp1, 1.14-1, 1.14-1~exp1, 1.14-1~exp2
Fixed versions: 1.13-1+deb13u1, 1.14-1
CVEs: CVE-2026-41991
Confirmed fixed CVEs: Not specified
Updated in this feed: 1 Nov 2026, 12:15 UTC · Revision 2

Source evidence

DEBIAN-CVE-2026-41991

core-osv · Original source

Published 29 Jun 2026, 12:16 UTC

osv:DEBIAN-CVE-2026-41991

gzip

Fixed versions: Not specified

gzip

Fixed versions: 1.13-1+deb13u1

gzip

Fixed versions: 1.14-1

Complete source record

{
  "id": "979c65516d30f9898c66e58ee95fb96c72e563460e4ec082e0f2a87326ff57d6",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2026-41991",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2026-41991",
    "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:DEBIAN-CVE-2026-41991",
    "products": [
      {
        "name": {
          "value": "gzip",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "1.12-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.12-1.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.12-1.2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.13-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.13.56~e549-1~exp1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.14-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.14-1~exp1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.14-1~exp2",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "gzip",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.13-1+deb13u1",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "1.13-1",
            "evidence": "/affected/1/versions"
          }
        ]
      },
      {
        "name": {
          "value": "gzip",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.14-1",
            "evidence": "/affected/2/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "1.13-1",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "1.13.56~e549-1~exp1",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "1.14-1~exp1",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "1.14-1~exp2",
            "evidence": "/affected/2/versions"
          }
        ]
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "DEBIAN-CVE-2026-41991",
      "aliases": [
        "DEBIAN-CVE-2026-41991"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "gzip",
            "purl": "pkg:deb/debian/gzip?arch=source&distro=bookworm",
            "ecosystem": "Debian:12"
          },
          "versions": [
            "1.12-1",
            "1.12-1.1",
            "1.12-1.2",
            "1.13-1",
            "1.13.56~e549-1~exp1",
            "1.14-1",
            "1.14-1~exp1",
            "1.14-1~exp2"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-41991.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1.13-1+deb13u1"
                }
              ]
            }
          ],
          "package": {
            "name": "gzip",
            "purl": "pkg:deb/debian/gzip?arch=source&distro=trixie",
            "ecosystem": "Debian:13"
          },
          "versions": [
            "1.13-1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-41991.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1.14-1"
                }
              ]
            }
          ],
          "package": {
            "name": "gzip",
            "purl": "pkg:deb/debian/gzip?arch=source&distro=forky",
            "ecosystem": "Debian:14"
          },
          "versions": [
            "1.13-1",
            "1.13.56~e549-1~exp1",
            "1.14-1~exp1",
            "1.14-1~exp2"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-41991.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-26T11:47:33.825000703Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-41991"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2026-41991"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-41991",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 450733,
  "published_at": "2026-06-29T12:16:29.77+00:00"
}