adm-zip: Duplicate ZIP entry names: getEntry() and extractAllTo() resolve to different content

{
  "id": "1a577a69bc50675f06c8a347d88f80f2ef86f12bed73af0deb0d0ad54f04c4bb",
  "url": "https://osv.dev/vulnerability/GHSA-p634-w6r4-rjp2",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "adm-zip: Duplicate ZIP entry names: getEntry() and extractAllTo() resolve to different content",
    "summary": "### Summary A ZIP file can contain two entries with the identical name. adm-zip keeps both in its internal entry list, but its name-lookup table only retains the last one written. `getEntry(name)` and `extractAllTo()` walk these two different internal structures, so they can each resolve a duplicate name to a *different* entry. An application that validates a named entry's contents via `getEntry()` before trusting an archive, then extracts the whole archive, can end up approving one file's content while a different file's bytes are what actually land on disk under that name. ### Details - `zipFile.js:58-83` retains both entries in `entryList` but overwrites `entryTable[name]` with only the last one written. - `adm-zip.js:83-95,658-663` uses `entryTable` for `getEntry()` lookups — returns the *last* duplicate. - `adm-zip.js:769-914` iterates `entryList` for extraction — writes the *first* duplicate (sync, default overwrite policy). ### PoC ```js const AdmZip = require('adm-zip'); const z = new AdmZip({ noSort: true }); z.addFile('a.txt', Buffer.from('FIRST')); z.addFile('b.txt', Buffer.from('SECOND')); const raw = Buffer.from(z.toBuffer()); // rename the a.txt entry to b.txt directly in the raw bytes for (let at = raw.indexOf('a.txt'); at >= 0; at = raw.indexOf('a.txt', at + 5)) { raw.write('b.txt', at); } const parsed = new AdmZip(raw, { noSort: true }); const validated = parsed.getEntry('b.txt').getData().toString(); parsed.extractAllTo(outDir, false); // validated === \"SECO",
    "evidence": "osv:GHSA-p634-w6r4-rjp2",
    "products": [
      {
        "name": {
          "value": "adm-zip",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "0.6.1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "GHSA-p634-w6r4-rjp2",
      "aliases": [
        "CVE-2026-114104",
        "GHSA-p634-w6r4-rjp2"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/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-p634-w6r4-rjp2/GHSA-p634-w6r4-rjp2.json",
            "last_known_affected_version_range": "<= 0.6.0"
          }
        }
      ],
      "modified": "2026-10-21T10:57:22.783519393Z",
      "provider": "osv",
      "references": [
        "https://github.com/cthackers/adm-zip/security/advisories/GHSA-p634-w6r4-rjp2",
        "https://github.com/cthackers/adm-zip/commit/05101d47b3b983b705cc3e66fc34366118ba7b99",
        "https://github.com/cthackers/adm-zip",
        "https://github.com/cthackers/adm-zip/releases/tag/v0.6.1"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-436",
          "CWE-696"
        ],
        "severity": "MODERATE",
        "github_reviewed": true,
        "nvd_published_at": null,
        "github_reviewed_at": "2026-09-29T23:11:01Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-114104",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 392976,
  "published_at": "2026-09-29T23:11:01+00:00"
}