# CVE-2021-37185: Denial of service in SIMATIC Drive Controller family > Unauthenticated attackers can cause a denial-of-service condition in Siemens SIMATIC PLCs by sending specially crafted packets, requiring a device restart to recover. - **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:O/RC:C`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** No - **Published:** 9 Feb 2022 - **Updated:** 18 Apr 2025 - **Also known as:** GHSA-pwf7-gchp-6gf8 ## What is CVE-2021-37185? CVE-2021-37185 is a high-severity denial of service vulnerability in Siemens SIMATIC Drive Controller family, published on 9 Feb 2022. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description A vulnerability has been identified in SIMATIC Drive Controller family (All versions >= V2.9.2 < V2.9.4), SIMATIC ET 200SP Open Controller CPU 1515SP PC2 (incl. SIPLUS variants) (All versions >= V21.9 < V21.9.4), SIMATIC S7-1200 CPU family (incl. SIPLUS variants) (All versions >= V4.5.0 < V4.5.2), SIMATIC S7-1500 CPU family (incl. related ET200 CPUs and SIPLUS variants) (All versions >= V2.9.2 < V2.9.4), SIMATIC S7-1500 Software Controller (All versions >= V21.9 < V21.9.4), SIMATIC S7-PLCSIM Advanced (All versions >= V4.0 < V4.0 SP1), SIPLUS TIM 1531 IRC (All versions < V2.3.6), TIM 1531 IRC (All versions < V2.3.6). An unauthenticated attacker could cause a denial-of-service condition in a PLC when sending specially prepared packets over port 102/tcp. A restart of the affected device is needed to restore normal operations. Weakness: CWE-672 (Operation on a Resource after Expiration or Release) ## Which versions are affected by CVE-2021-37185? It affects 48 products. Products: Siemens Simatic Drive Controller Cpu 1504d Tf Firmware, Siemens Simatic Drive Controller Cpu 1507d Tf Firmware, Siemens Simatic Et 200sp Open Controller Cpu 1515sp Pc2 Firmware, Siemens Simatic S7-1200 Cpu 1211c Firmware, Siemens Simatic S7-1200 Cpu 1212c Firmware, Siemens Simatic S7-1200 Cpu 1212fc Firmware, Siemens Simatic S7-1200 Cpu 1214c Firmware, Siemens Simatic S7-1200 Cpu 1214fc Firmware, Siemens Simatic S7-1200 Cpu 1215c Firmware, Siemens Simatic S7-1200 Cpu 1215fc Firmware, Siemens Simatic S7-1200 Cpu 1217c Firmware, Siemens Simatic S7-1500 Cpu 1510sp-1 Firmware, Siemens Simatic S7-1500 Cpu 1510sp Firmware, Siemens Simatic S7-1500 Cpu 1511-1 Firmware, Siemens Simatic S7-1500 Cpu 1511c-1 Firmware, Siemens Simatic S7-1500 Cpu 1511f-1 Firmware, Siemens Simatic S7-1500 Cpu 1511t-1 Firmware, Siemens Simatic S7-1500 Cpu 1511tf-1 Firmware, Siemens Simatic S7-1500 Cpu 1512c-1 Firmware, Siemens Simatic S7-1500 Cpu 1512sp-1 Firmware and 28 more. ## How do I fix CVE-2021-37185? No fix has been published for CVE-2021-37185 yet. Limit exposure of the affected software until one is available. ## Is CVE-2021-37185 being exploited? There is no known exploitation of CVE-2021-37185 in the wild and no public exploit code. ## Other vulnerabilities in Siemens SIMATIC Drive Controller family - [CVE-2022-38465](https://insights.sbomify.com/CVE-2022-38465/): Weak cryptography in SIMATIC Drive Controller family (critical 9.3) - [CVE-2023-46156](https://insights.sbomify.com/CVE-2023-46156/): Use after free in SIMATIC Drive Controller CPU 1504D TF (high 7.5) - [CVE-2021-37204](https://insights.sbomify.com/CVE-2021-37204/): Denial of service in SIMATIC Drive Controller family (high 7.5) - [CVE-2021-37205](https://insights.sbomify.com/CVE-2021-37205/): Denial of service in SIMATIC Drive Controller family (high 7.5) - [CVE-2022-38773](https://insights.sbomify.com/CVE-2022-38773/): Security feature bypass in SIMATIC Drive Controller CPU 1504D TF (medium 4.6) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2021-37185 and fix it if it is affected. What it is: CVE-2021-37185 is a high-severity denial of service vulnerability in Siemens SIMATIC Drive Controller family, published on 9 Feb 2022. 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-2021-37185 in the wild and no public exploit code. Affected product: Siemens SIMATIC Drive Controller family. 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-2021-37185/ (Markdown: https://insights.sbomify.com/CVE-2021-37185/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2021-37185 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-37185 - OSV: https://osv.dev/vulnerability/CVE-2021-37185 --- From sbomify Insights: https://insights.sbomify.com/CVE-2021-37185/ Summaries are generated and may contain mistakes; the official description above is the record.