adm-zip extraction preserves SUID/SGID bits from untrusted ZIPs -> local privilege escalation

{
  "id": "1c0d76af4f798db45b3ec1a68f3ae563ccf33f9da14d3f8bbca42ccd00c94565",
  "url": "https://osv.dev/vulnerability/GHSA-j5f4-cc29-5x44",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "adm-zip extraction preserves SUID/SGID bits from untrusted ZIPs -> local privilege escalation",
    "summary": "## Summary adm-zip applies the Unix permission bits stored in a zip entry directly to the extracted file via `fs.chmodSync()` when `keepOriginalPermission=true` is passed to `extractAllTo()`/`extractEntryTo()` — and it never filters the setuid/setgid/sticky bits out of those bits. A zip crafted by an attacker can therefore produce an extracted binary with mode `04755`. When extraction runs as root (the default posture in Docker builds, CI runners, and privileged install steps — the exact environments where this flag is used), the resulting root-owned setuid file is executed later by a lesser-privileged user, turning the attacker's code into a root execution. ## Details The mode a zip entry wants is read back from the external file attributes in the header, and the mask used keeps every special bit: ```js // headers/entryHeader.js:187 get fileAttr() { return (_attr || 0) >> 16 & 0xfff; } ``` `0xfff` is `0o7777` — it preserves setuid (`0o4000`), setgid (`0o2000`) and the sticky bit (`0o1000`) along with the rwx bits. Shifting by 16 is the standard Unix convention for where zip stores the mode; the mask is the problem. When the flag is on, that value goes straight to the write: ```js // adm-zip.js:726-727 (extractEntryTo, and identically in extractAllTo) const fileAttr = keepOriginalPermission ? entry.header.fileAttr : undefined; filetools.writeFileTo(target, content, overwrite, fileAttr); ``` ```js // util/utils.js:94 self.fs.chmodSync(path, attr || 0o666); ``` No `& 0o777`, no",
    "evidence": "osv:GHSA-j5f4-cc29-5x44",
    "products": [
      {
        "name": {
          "value": "adm-zip",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "0.6.1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "GHSA-j5f4-cc29-5x44",
      "aliases": [
        "CVE-2026-102282",
        "GHSA-j5f4-cc29-5x44"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "0.6.1"
                }
              ]
            }
          ],
          "package": {
            "name": "adm-zip",
            "purl": "pkg:npm/adm-zip",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-j5f4-cc29-5x44/GHSA-j5f4-cc29-5x44.json",
            "last_known_affected_version_range": "<= 0.6.0"
          }
        }
      ],
      "modified": "2026-10-08T10:56:40.691028011Z",
      "provider": "osv",
      "references": [
        "https://github.com/cthackers/adm-zip/security/advisories/GHSA-j5f4-cc29-5x44",
        "https://github.com/cthackers/adm-zip/commit/6a63c339b83c52915483efacda517660a7a7bf87",
        "https://github.com/cthackers/adm-zip",
        "https://github.com/cthackers/adm-zip/releases/tag/v0.6.1"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-732"
        ],
        "severity": "HIGH",
        "github_reviewed": true,
        "nvd_published_at": null,
        "github_reviewed_at": "2026-09-29T18:24:57Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-102282",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 99128,
  "published_at": "2026-09-29T18:24:57+00:00"
}