Critical 9.4Published Oct 1, 2026

CVE-2026-94620Classroom 50 vulnerable to arbitrary file overwrite on the teacher's machine via symlink in a student repo (gh teacher download)

Updated under an hour ago (2026-10-19 08:30 UTC)

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It affects foundation50 classroom50. Add what you run to find out whether that includes you.

EPSS puts the chance of exploitation in the next 30 days at 0.41%, higher than 34% of scored CVEs.

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Exploited in the last 30 days

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.

CVSS: 9.4 CRITICAL (v4.0, CNA)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
Weakness (CWE): CWE-22, CWE-59
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): 0.41% (percentile 34)
Assigned by: GitHub_M
NVD analysis: Deferred
Record last updated: Oct 1, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

foundation50 classroom50 foundation50:classroom50 (from the name)	before 1.11.0	CNA record

References

https://github.com/foundation50/classroom50/security/advisories/GHSA-qx2g-vpwq-466cx-refsource-confirm
https://github.com/foundation50/classroom50/commit/79112f33932d1b5c398a8801d97a8813d52d55cex-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.