CVE-2026-35556
Published: 09 April 2026
Summary
CVE-2026-35556 is a critical-severity Plaintext Storage of a Password (CWE-256) vulnerability in Openplcproject Openplc V3 Firmware. Its CVSS base score is 9.2 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Unsecured Credentials (T1552); ranked at the 21.2th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 IA-5 (Authenticator Management) and SC-28 (Protection of Information at Rest).
Deeper analysis
CVE-2026-35556 is a Plaintext Storage of a Password vulnerability (CWE-256) in OpenPLC_V3, published on 2026-04-09. The issue enables attackers to retrieve credentials stored in plaintext, potentially granting access to sensitive information. It carries a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N), indicating high confidentiality impact with network accessibility and low attack complexity.
An unauthenticated attacker (PR:N) can exploit this vulnerability remotely over the network (AV:N) without requiring user interaction (UI:N). Exploitation involves accessing the affected component to extract plaintext credentials, allowing unauthorized disclosure of sensitive information (C:H) while leaving integrity and availability unaffected.
The CISA ICS Advisory ICSA-25-345-10 provides further details on this vulnerability, including potential mitigation steps, at https://www.cisa.gov/news-events/ics-advisories/icsa-25-345-10.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-21041
Vulnerability details
OpenPLC_V3 is vulnerable to a Plaintext Storage of a Password vulnerability that could allow an attacker to retrieve credentials and access sensitive information.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
The vulnerability is explicitly plaintext storage of passwords (CWE-256), directly enabling retrieval of unsecured credentials as described in T1552 Unsecured Credentials.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Requires cryptographic mechanisms to protect confidentiality of sensitive information at rest, directly preventing retrieval of plaintext-stored passwords.
Mandates protection of authenticators like passwords during storage commensurate with the sensitivity of protected information.
Requires timely identification, reporting, and correction of flaws such as plaintext password storage in this specific CVE.