CVE-2026-81574: Format String Vulnerability in Logger
In CodeMeter Runtime before versions 8.41a and 9.10, the logger does not sanitize input strings in certain cases, allowing an attacker to inject printf-style format specifiers. This can be used to reliably crash CodeMeter and disclose sensitive information such as process memory and stack canaries. The attack works locally, for example by using cmu --set-proxy to set the proxy value, and remotely when combined with CVE-2026-81573 by setting General.ProxyServer and then triggering this vulnerability.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
CodeMeter Runtimeto a version that resolves this vulnerability.Fixed in 8.41a - Upgrade
Upgrade
CodeMeter Runtimeto a version that resolves this vulnerability.Fixed in 9.10 - Configuration
Do not set General.ProxyServer (or related proxy fields such as via cmu --set-proxy) to attacker-controlled values, since malformed/specified strings combined with CVE-2026-81573 can trigger the format-specifier injection remotely.
CodeMeter (General.ProxyServer / proxy configuration) General.ProxyServer = Do not set/avoid using attacker-controlled proxy values - Compensating control
If feasible, limit or isolate access that allows local attackers to run cmu --set-proxy or change CodeMeter proxy settings, to prevent local exploitation via unsanitized logger format strings.
Event History
Frequently Asked Questions
Which deployments are exposed to remote exploitation?
Remote exploitation requires this issue to be combined with CVE-2026-81573. An attacker must set General.ProxyServer and then trigger the unsafe logging behavior.
Can an unauthenticated local user exploit this issue?
Yes. The local attack example uses cmu --set-proxy to set a proxy value containing printf-style format specifiers; no privileges or user interaction are indicated by the supplied vector.
What can exploitation accomplish?
An attacker can reliably crash CodeMeter, causing a denial of service. The format-string flaw can also disclose sensitive information, including process memory and stack canaries.
Which versions need remediation?
CodeMeter Runtime versions before 8.41a and before 9.10 are affected. Update to 8.41a, 9.10, or a later version as applicable.