How severe is CVE-2020-8515?

CVE-2020-8515 has a CVSS score of 9.8/10, rated CRITICAL. Immediate patching is strongly recommended.

Which products are affected by CVE-2020-8515?

Affected package information for CVE-2020-8515 is not yet fully mapped. Check the official advisory links for details.

How do I patch CVE-2020-8515?

No patch has shipped for CVE-2020-8515 yet — track the draytek vigor300b firmware advisory for a fixed release and apply the workarounds below in the meantime.

How do I detect CVE-2020-8515 across my infrastructure?

Inventory every draytek vigor300b firmware deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for remote code execution at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.

How do I mitigate CVE-2020-8515 if there is no patch (or I can't update yet)?

Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.

How does O3 Security protect against CVE-2020-8515?

O3 detects and blocks CVE-2020-8515 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.

Is CVE-2020-8515 actively exploited in the wild?

Yes. There are 13 known exploit references for CVE-2020-8515, including 1 documented proof-of-concept exploit on Exploit-DB and 9 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2020-8515?

CVE-2020-8515 has an EPSS (Exploit Prediction Scoring System) score of 100.0%, placing it in the 100th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

Is CVE-2020-8515 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2020-8515 (Multiple DrayTek Vigor Routers Web Management Page Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2021-11-03. CISA required all US federal civilian agencies to remediate this vulnerability by 2022-05-03. The required action was: Apply updates per vendor instructions. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2020-8515?

CVE-2020-8515 is classified as OS Command Injection (CWE-78). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

Which products and versions are affected by CVE-2020-8515?

CVE-2020-8515 affects draytek vigor300b firmware (3 versions, e.g. 1.3.3, 1.4.2.1, 1.4.4); draytek vigor2960 firmware (1 version, e.g. 1.3.1); draytek vigor3900 firmware (1 version, e.g. 1.4.4). Check the affected-products list on this page against your deployed version to confirm exposure.

Is there exploit tooling available for CVE-2020-8515?

A Nuclei detection template exists for CVE-2020-8515, meaning automated scanners can fingerprint it. Public exploit tooling significantly increases real-world risk — prioritize patching and ensure detection coverage. Exploit tooling should only ever be used in isolated, authorized testing environments.

When was CVE-2020-8515 published, and has it been updated?

CVE-2020-8515 was published on February 1, 2020 and was last updated on June 17, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CISA KEV·Added 2021-11-03 — agencies required to remediate by 2022-05-03

CVE-2020-8515

CRITICAL

DrayTek Vigor2960 1.3.1_Beta, Vigor3900 1.4.4_Beta, and Vigor300B 1.3.3_Beta, 1.4.2.1_Beta, and 1.4.4_Beta devices allow remote code execution as root (without authentication) via shell…

Published

Feb 1, 2020

Updated

Jun 17, 2026

Affected

0 pkgs

Patched

None yet

Exploits

13 known

EPSS Exploitation Probability

via FIRST.org ↗

100.0%probability of exploitation in next 30 days

Very High Risk100th percentile0.00%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Description

DrayTek Vigor2960 1.3.1_Beta, Vigor3900 1.4.4_Beta, and Vigor300B 1.3.3_Beta, 1.4.2.1_Beta, and 1.4.4_Beta devices allow remote code execution as root (without authentication) via shell metacharacters to the cgi-bin/mainfunction.cgi URI. This issue has been fixed in Vigor3900/2960/300B v1.5.1.

Affected Products

3 products · 5 configurations

vigor300b firmwaredraytek

3 versions

1.3.31.4.2.11.4.4

vigor2960 firmwaredraytek

1 version

1.3.1

vigor3900 firmwaredraytek

1 version

1.4.4

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

EDB-48268remotelinux

Multiple DrayTek Products - Pre-authentication Remote Root Code Execution

by 0xsha · Mar 30, 2020

Exploit-DB Source

Detection & mitigation playbook

Vendor / appliance

Detect
Inventory every draytek vigor300b firmware deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for remote code execution at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.
Remediation status
No patch has shipped for CVE-2020-8515 yet — track the draytek vigor300b firmware advisory for a fixed release and apply the workarounds below in the meantime.
Mitigate without a patch
Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.
How O3 protects you
O3 detects and blocks CVE-2020-8515 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.

Tailored to CVE-2020-8515. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

O3 Security · Runtime Protection

Is CVE-2020-8515 being exploited in your environment?

O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2020-8515 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.

Protect my workloads How runtime protection works

CVE-2020-8515

EPSS Exploitation Probability

Description

Affected Products

Detection & mitigation playbook

Detect

Remediation status

Mitigate without a patch

How O3 protects you

Frequently Asked Questions

Is CVE-2020-8515 being exploited in your environment?