Classroom 50 vulnerable to arbitrary file overwrite on the teacher's machine via symlink in a student repo (gh teacher download)
Summary
| CVE | CVE-2026-94620 |
|---|---|
| State | PUBLISHED |
| Assigner | GitHub_M |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-10-01 16:18:08 UTC |
| Updated | 2026-10-01 17:17:33 UTC |
| Description | 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. |
Risk And Classification
Primary CVSS: v4.0 9.4 CRITICAL from [email protected]
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Problem Types: CWE-22 | CWE-59 | CWE-22 CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') | CWE-59 CWE-59: Improper Link Resolution Before File Access ('Link Following')
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 9.4 | CRITICAL | 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/E:X/C... |
| 4.0 | CNA | DECLARED | 9.4 | CRITICAL | 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 |
CVSS v4.0 Breakdown
Attack Vector
NetworkAttack Complexity
LowAttack Requirements
NonePrivileges Required
NoneUser Interaction
PassiveConfidentiality
HighIntegrity
HighAvailability
HighSub Conf.
HighSub Integrity
HighSub Availability
HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Foundation50 | Classroom50 | affected < 1.11.0 | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/foundation50/classroom50/security/advisories/GHSA-qx2g-vpwq-466c | [email protected] | github.com | |
| github.com/foundation50/classroom50/commit/79112f33932d1b5c398a8801d97a8... | [email protected] | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.