Vulnerability in Cacti
CVE-2026-39894
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 2.9 (Low). Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N.
EPSS exploit prediction
EPSS: 0.001 (2.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 3rd percentile — 2.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.001 · newest: 0.001 · change: 0.000
Affected products
- Cacti — versions < 1.2.31
Weakness classification (CWE)
References
- github.com/Cacti/cacti/commit/d2a698854956e9e4e53da9eab5b5719ae40e6893 (Patch)
- github.com/Cacti/cacti/issues/7011 (Patch, Issue Tracking)
- github.com/Cacti/cacti/security/advisories/GHSA-23g4-vf2j-94w4 (Vendor Advisory)
Frequently asked questions
- What is CVE-2026-39894?
- CVE-2026-39894 is a low-severity vulnerability in Cacti, classified under CWE-474. CVSS score: 2.9/10. Published 2026-06-24.
- How severe is CVE-2026-39894?
- Low severity. CVSS v3 base score is 2.9 out of 10.