# CVE-2021-20716: Security feature bypass in Buffalo network devices > Remote attackers can exploit hidden debug functionality in Buffalo network devices to execute arbitrary code, modify configurations, or cause denial of service. - **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** No - **Published:** 28 Apr 2021 - **Updated:** 3 Aug 2024 - **Also known as:** GHSA-76mj-jfgj-cfq9 ## What is CVE-2021-20716? CVE-2021-20716 is a critical vulnerability in Buffalo network devices, published on 28 Apr 2021. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description Hidden functionality in multiple Buffalo network devices (BHR-4RV firmware Ver.2.55 and prior, FS-G54 firmware Ver.2.04 and prior, WBR2-B11 firmware Ver.2.32 and prior, WBR2-G54 firmware Ver.2.32 and prior, WBR2-G54-KD firmware Ver.2.32 and prior, WBR-B11 firmware Ver.2.23 and prior, WBR-G54 firmware Ver.2.23 and prior, WBR-G54L firmware Ver.2.20 and prior, WHR2-A54G54 firmware Ver.2.25 and prior, WHR2-G54 firmware Ver.2.23 and prior, WHR2-G54V firmware Ver.2.55 and prior, WHR3-AG54 firmware Ver.2.23 and prior, WHR-G54 firmware Ver.2.16 and prior, WHR-G54-NF firmware Ver.2.10 and prior, WLA2-G54 firmware Ver.2.24 and prior, WLA2-G54C firmware Ver.2.24 and prior, WLA-B11 firmware Ver.2.20 and prior, WLA-G54 firmware Ver.2.20 and prior, WLA-G54C firmware Ver.2.20 and prior, WLAH-A54G54 firmware Ver.2.54 and prior, WLAH-AM54G54 firmware Ver.2.54 and prior, WLAH-G54 firmware Ver.2.54 and prior, WLI2-TX1-AG54 firmware Ver.2.53 and prior, WLI2-TX1-AMG54 firmware Ver.2.53 and prior, WLI2-TX1-G54 firmware Ver.2.20 and prior, WLI3-TX1-AMG54 firmware Ver.2.53 and prior, WLI3-TX1-G54 firmware Ver.2.53 and prior, WLI-T1-B11 firmware Ver.2.20 and prior, WLI-TX1-G54 firmware Ver.2.20 and prior, WVR-G54-NF firmware Ver.2.02 and prior, WZR-G108 firmware Ver.2.41 and prior, WZR-G54 firmware Ver.2.41 and prior, WZR-HP-G54 firmware Ver.2.41 and prior, WZR-RS-G54 firmware Ver.2.55 and prior, and WZR-RS-G54HP firmware Ver.2.55 and prior) allows a remote attacker to enable the debug option and to execute arbitrary code or OS commands, change the configuration, and cause a denial of service (DoS) condition. ## Which versions are affected by CVE-2021-20716? It affects 35 products. Products: Buffalo Bhr-4rv Firmware, Buffalo Fs-G54 Firmware, Buffalo Wbr-B11 Firmware, Buffalo Wbr-G54 Firmware, Buffalo Wbr-G54l Firmware, Buffalo Wbr2-B11 Firmware, Buffalo Wbr2-G54-Kd Firmware, Buffalo Wbr2-G54 Firmware, Buffalo Whr-G54-Nf Firmware, Buffalo Whr-G54 Firmware, Buffalo Whr2-A54g54 Firmware, Buffalo Whr2-G54 Firmware, Buffalo Whr2-G54v Firmware, Buffalo Whr3-Ag54 Firmware, Buffalo Wla-B11 Firmware, Buffalo Wla-G54 Firmware, Buffalo Wla-G54c Firmware, Buffalo Wla2-G54 Firmware, Buffalo Wla2-G54c Firmware, Buffalo Wlah-A54g54 Firmware and 15 more. ## How do I fix CVE-2021-20716? No fix has been published for CVE-2021-20716 yet. Limit exposure of the affected software until one is available. ## Is CVE-2021-20716 being exploited? There is no known exploitation of CVE-2021-20716 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2021-20716 and fix it if it is affected. What it is: CVE-2021-20716 is a critical vulnerability in Buffalo network devices, published on 28 Apr 2021. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: There is no known exploitation of CVE-2021-20716 in the wild and no public exploit code. Affected product: Buffalo network devices. No package-level version data is available, so check the vendor advisory linked from the reference page. Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2021-20716/ (Markdown: https://insights.sbomify.com/CVE-2021-20716/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2021-20716 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-20716 - OSV: https://osv.dev/vulnerability/CVE-2021-20716 --- From sbomify Insights: https://insights.sbomify.com/CVE-2021-20716/ Summaries are generated and may contain mistakes; the official description above is the record.