Classroom 50 vulnerable to arbitrary file overwrite on the teacher's machine via symlink in a student repo (gh teacher download)

{
  "id": "c7671b9c1e5cf490d33c0fe6747bd0334eeb974ebb7e75562bf51976de63110f",
  "url": "https://osv.dev/vulnerability/CVE-2026-94620",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Classroom 50 vulnerable to arbitrary file overwrite on the teacher's machine via symlink in a student repo (gh teacher download)",
    "summary": "Classroom 50 is a free and open-source tool for managing and grading programming assignments via GitHub. Prior to version 1.11.0, `gh teacher download` clones each student's assignment repository and then writes autograde artifacts (`result.json` and `results.json`) into the just-cloned working tree. The write followed symlinks, so a student who committed `result.json` or `results.json` as a **symlink** (materialized verbatim by `git clone`) could redirect the teacher's write to an arbitrary path — e.g. `~/.zshrc`, `~/.ssh/authorized_keys`, a cron file, or an in-clone `.git/hooks/*` file that git subsequently executes. The written bytes are attacker-controlled (the student's uploaded release asset for `result.json`; student-chosen submit-tag names for `results.json`). This is an arbitrary file write leading to code execution as the teacher, whose `gh` token carries `admin:org`, `repo`, and `workflow` across the entire classroom organization. Version 1.11.0 contains a patch. Some workarounds are available. Avoid running `gh teacher download` against untrusted student repositories, or run it inside a disposable sandbox / container with no access to sensitive host files or credentials. Inspect cloned trees for symlinked, hardlinked, or special (`result.json`/`results.json`) entries before allowing the artifact-refresh step to run.",
    "evidence": "osv:CVE-2026-94620",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-94620",
      "aliases": [
        "CVE-2026-94620",
        "GHSA-qx2g-vpwq-466c"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/foundation50/classroom50",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "42d5d7285946059bf374875764539127ac3c6599"
                },
                {
                  "fixed": "79112f33932d1b5c398a8801d97a8813d52d55ce"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.11.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "79112f33932d1b5c398a8801d97a8813d52d55ce"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "web-v1.10.0",
            "cli-v1.10.0",
            "web-v1.9.0",
            "cli-v1.9.0",
            "web-v1.8.0",
            "cli-v1.8.0",
            "web-v1.7.0",
            "cli-v1.7.0",
            "web-v1.6.0",
            "cli-v1.6.0",
            "web-v1.5.0",
            "cli-v1.5.0",
            "web-v1.4.0",
            "cli-v1.4.0",
            "web-v1.3.0",
            "cli-v1.3.0",
            "web-v1.2.0",
            "cli-v1.2.0",
            "web-v1.1.0",
            "cli-v1.1.0",
            "web-v1.0.0",
            "cli-v1.0.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-94620.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:50.040499361Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/94xxx/CVE-2026-94620.json",
        "https://github.com/foundation50/classroom50/security/advisories/GHSA-qx2g-vpwq-466c",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-94620",
        "https://github.com/foundation50/classroom50/commit/79112f33932d1b5c398a8801d97a8813d52d55ce"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-22",
          "CWE-59"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/94xxx/CVE-2026-94620.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-94620",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 518462,
  "published_at": "2026-10-01T15:38:09.062+00:00"
}