# CVE-2025-3756: Denial of Service Vulnerabilities in System 800xA, Symphony® Plus IEC 61850 > An attacker on IEC 61850 networks can cause denial of service in ABB System 800xA and Symphony Plus communication modules via crafted packets. - **Severity:** High 7.1 (`CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Local or same network only - **Victim action needed:** Not needed - **Fix available:** No - **Published:** 13 Apr 2026 - **Updated:** 13 Apr 2026 - **Also known as:** GHSA-h84p-pw6f-c6p6 ## What is CVE-2025-3756? CVE-2025-3756 is a high-severity denial of service vulnerability in ABB AC800M (System 800xA), published on 13 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim. ### Official description A vulnerability exists in the command handling of the IEC 61850 communication stack included in the product revisions listed as affected in this CVE. An attacker with access to IEC 61850 networks could exploit the vulnera bility by using a specially crafted 61850 packet, forcing the communication interfaces of the PM 877, CI850 and CI868 modules into fault mode or causing unavailability of the S+ Operations 61850 connectivity, resulting in a denial-of-service situation.  The System 800xA IEC61850 Connect is not affected. Note: This vulnerability does not impact on the overall availability and functionality of the S+ Operations node, only the 61850 communication function.     This issue affects AC800M (System 800xA): from 6.0.0x through 6.0.0303.0, from 6.1.0x through 6.1.0031.0, from 6.1.1x through 6.1.1004.0, from 6.1.1x through 6.1.1202.0, from 6.2.0x through 6.2.0006.0; Symphony Plus SD Series: A_0, A_1, A_2.003, A_3.005, A_4.001, B_0.005; Symphony Plus MR (Melody Rack): from 3.10 through 3.52; S+ Operations: 2.1, 2.2, 2.3, 3.3. Weakness: CWE-1284 (Improper Validation of Specified Quantity in Input) ## Which versions are affected by CVE-2025-3756? ## How do I fix CVE-2025-3756? No fix has been published for CVE-2025-3756 yet. Limit exposure of the affected software until one is available. ## Is CVE-2025-3756 being exploited? There is no known exploitation of CVE-2025-3756 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2025-3756 and fix it if it is affected. What it is: CVE-2025-3756 is a high-severity denial of service vulnerability in ABB AC800M (System 800xA), published on 13 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim. Exploitation: There is no known exploitation of CVE-2025-3756 in the wild and no public exploit code. Affected product: ABB AC800M (System 800xA). 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-2025-3756/ (Markdown: https://insights.sbomify.com/CVE-2025-3756/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2025-3756 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-3756 - OSV: https://osv.dev/vulnerability/CVE-2025-3756 --- From sbomify Insights: https://insights.sbomify.com/CVE-2025-3756/ Summaries are generated and may contain mistakes; the official description above is the record.