Critical severity · published Oct 1, 2026
CVE-2026-94620
Classroom 50 vulnerable to arbitrary file overwrite on the teacher's machine via symlink in a student repo (gh teacher download)
9.4
CVSS
0.4%
EPSS
No
On KEV
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.
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 36% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CL
classroom50 · foundation50
< 1.11.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-94620
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-94620
x_refsource_CONFIRM
https://github.com/foundation50/classroom50/security/advisories/GHSA-qx2g-vpwq-466c
x_refsource_MISC
https://github.com/foundation50/classroom50/commit/79112f33932d1b5c398a8801d97a8813d52d55ce
