CVE-2020-15415 — Vigor300b Firmware
CRITICALCVE-2020-15415 is a critical-severity (CVSS 9.8) OS Command Injection vulnerability in draytek vigor300b firmware. It is in CISA's Known Exploited Vulnerabilities catalog (added 2024-09-30) — treat it as actively exploited and patch now. No vendor fix is recorded yet; mitigation options are listed below.
On DrayTek Vigor3900, Vigor2960, and Vigor300B devices before 1.5.1, cgi-bin/mainfunction.cgi/cvmcfgupload allows remote command execution via shell metacharacters in a filename when…
Exploitation Status
Actively exploited in the wild
- Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2024-09-30. Federal agencies were required to remediate by 2024-10-21.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2020-15415.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2020-15415 by exploitation likelihood (EPSS) against impact (CVSS). In the shaded patch-first corner (EPSS 50%+, CVSS 7.0+).
Where this sits among everything scored
Of 395,249 CVEs with a current EPSS score, this one falls in the 50–90% band (highlighted). Counts from FIRST.org, log-scaled.
Description
On DrayTek Vigor3900, Vigor2960, and Vigor300B devices before 1.5.1, cgi-bin/mainfunction.cgi/cvmcfgupload allows remote command execution via shell metacharacters in a filename when the text/x-python-script content type is used, a different issue than CVE-2020-14472.
Affected Products
vigor300b firmwaredraytekvigor2960 firmwaredraytekvigor3900 firmwaredraytekResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Vendor / applianceDetect
Inventory every draytek vigor300b firmware deployment and check each version against the affected-products list above.
Remediation status
No patch has shipped for CVE-2020-15415 yet — track the draytek vigor300b firmware advisory for a fixed release and apply the workarounds below in the meantime.
Mitigate without a patch
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.
How to detect CVE-2020-15415
A community-maintained Nuclei template exists for this CVE. You can scan for it directly:
nuclei -id cve-2020-15415 -u https://target- Template
- DrayTek Vigor - Command Injection
- Severity
- critical
- Impact
- Unauthenticated attackers can execute arbitrary system commands on DrayTek Vigor devices via the cvmcfgupload endpoint, leading to complete device compromise and potential network infiltration.
- Remediation
- Update the firmware to the latest version provided by DrayTek. If no update is available, consider implementing network segmentation to restrict access to the device's management interface.
Template by ProjectDiscovery nuclei-templates (ritikchaddha), MIT licensed. View the full template. Scan only systems you are authorised to test.
Frequently Asked Questions
Is CVE-2020-15415 being exploited in your environment?
Detect and block the exploit chain at execution, on systems you cannot patch yet.