How severe is CVE-2020-12256?

No CVSS score has been assigned to CVE-2020-12256 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2020-12256?

Affected package information for CVE-2020-12256 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2020-12256?

No fixed release is recorded for CVE-2020-12256 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.

How do I detect CVE-2020-12256 in my code and dependencies?

Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).

How do I mitigate CVE-2020-12256 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is CVE-2020-12256 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2020-12256, including 1 in-the-wild exploitation 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-2020-12256?

CVE-2020-12256 has an EPSS (Exploit Prediction Scoring System) score of 95.9%, 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.

What type of vulnerability is CVE-2020-12256?

CVE-2020-12256 is classified as Cross-site Scripting (XSS) (CWE-79). 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.

Is there exploit tooling available for CVE-2020-12256?

A Nuclei detection template exists for CVE-2020-12256, 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-2020-12256 published, and has it been updated?

CVE-2020-12256 was published on May 18, 2020 and was last updated on August 4, 2024. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

Not in CISA KEV

CVE-2020-12256 — Farid007

CVE-2020-12256 is a Cross-site Scripting (XSS) vulnerability. 1 public exploit reference exists, so weaponization risk is real. No vendor fix is recorded yet; mitigation options are listed below.

rConfig 3.9.4 is vulnerable to reflected XSS. The devicemgmnt.php file improperly validates user input. An attacker can exploit this by crafting arbitrary JavaScript in the deviceId…

Published

May 18, 2020

Updated

Aug 4, 2024

Affected

1 product

Patched

See advisory

Exploits

1 known

Exploitation data as of Oct 27, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

95.9%probability of exploitation in next 30 days

Very High Risk+0.18%

Lower risk than most CVEs100th percentile — riskier than 100% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Description

rConfig 3.9.4 is vulnerable to reflected XSS. The devicemgmnt.php file improperly validates user input. An attacker can exploit this by crafting arbitrary JavaScript in the deviceId GET parameter to devicemgmnt.php.

Affected Products

1 product · 1 configurations

Application

rconfigrconfig

1 version

3.9.4

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.

rConfig 3.9.4 is vulnerable to reflected XSS. The devicemgmnt.php file i…

gist.github.comNVDMay 2020

Detection & mitigation playbook

Vulnerability

Detect
Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).
Remediation status
No fixed release is recorded for CVE-2020-12256 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.
Mitigate without a patch
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

How to detect CVE-2020-12256

A community-maintained Nuclei template exists for this CVE. You can scan for it directly:

nuclei -id cve-2020-12256 -u https://target

Template: rConfig 3.9.4 - Cross-Site Scripting
Severity: medium
Impact: Authenticated attackers can inject malicious JavaScript through the deviceId parameter, potentially stealing session cookies or performing administrative actions on behalf of authenticated users.
Remediation: Upgrade to rConfig version 3.9.7 or later.

Template by ProjectDiscovery nuclei-templates (r3Y3r53), MIT licensed. View the full template. Scan only systems you are authorised to test.

Frequently Asked Questions

O3 Security · Impact-Aware SCA

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