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.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
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
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.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-3756 being exploited?
There is no known exploitation of CVE-2025-3756 in the wild and no public exploit code.
Sources
Also known as GHSA-h84p-pw6f-c6p6.