CVE-2026-39894
LOWDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 4% of all known CVEs.
References
Related Vulnerabilities
Other CWE-474 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2021-0294 | Medium | 5.3 | 0.9% | - | - |
| CVE-2024-1672 | Medium | 5.4 | 0.9% | - | Fix |
| CVE-2024-2628 | Medium | 4.3 | 0.6% | - | Fix |
| CVE-2026-25960 | High | 7.1 | 0.5% | - | Fix |
| CVE-2024-5836 | High | 8.8 | 0.5% | - | Fix |
| CVE-2024-5839 | Medium | 6.5 | 0.5% | - | Fix |
Common questions
How do I fix CVE-2026-39894?
Upgrade cacti on debian unstable to 1.2.31+ds1-1 or later.
Is CVE-2026-39894 being actively exploited?
Not that we know of. CVE-2026-39894 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.15% is the estimated probability that it will be exploited in the next 30 days. That is higher than 4% of all scored CVEs.
How severe is CVE-2026-39894?
CVE-2026-39894 has a CVSS v3 base score of 2.9, rated low. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-39894 affect?
Published advisories record a fix for cacti (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-25.