CVE-2026-39894
LowCVSS 2.9Exploitation Probability (EPSS)
Low risk1th percentile — higher than 1% of all known CVEs
Summary
In Cacti versions 1.2.30 and below, the locale-dependent decimal formatting in rrdtool_function_update() can corrupt RRDtool metric values. When the server locale uses comma as decimal separator (e.g., de_DE), a value of 1.5 becomes '1,5', while RRDtool expects a dot. This causes metric data to shift into wrong columns or be silently dropped.
Risk Assessment
The risk is loss of data integrity in Cacti-monitored metrics, potentially leading to incorrect readings and false alerts. The vulnerability is not remotely exploitable and requires server locale misconfiguration.
Recommendation
Update Cacti to version 1.2.31 or later immediately. Additionally, verify and set the server locale (LC_NUMERIC) to a value using dot as decimal separator.
Original NVD description (English source)
Cacti is an open source performance and fault management framework. In versions 1.2.30 and below, the locale-dependent decimal formatting in rrdtool_function_update() can corrupt RRDtool metric values. The rrdtool_function_update() function checks metric values with is_numeric() and concatenates them into the RRDtool update command via PHP string interpolation. PHP's string cast of floats is locale-sensitive: if LC_NUMERIC uses comma as decimal separator (e.g., de_DE), a value of 1.5 becomes "1,5". RRDtool expects . as decimal separator, causing metric data to shift into wrong columns or be silently dropped. No setlocale() reset is present in the update path. This causes a data integrity issue, but is not remotely exploitable; it requires server locale misconfiguration. The issue has been fixed in version 1.2.31.