Vulnerability · Published Jun 24, 2026 · Assigned by GitHub_M

CVE-2026-39894Cacti: RRDtool metric shift via LC_NUMERIC locale comma decimal formatting

Low 2.9

In plain English

A low-severity security flaw in cacti from Cacti. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 3% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)2.9Low

Exploit odds (30 days)0.1%top 96.7% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	cacti	no fix listed	DEBIAN-CVE-2026-39894
Debian:13	cacti	no fix listed	DEBIAN-CVE-2026-39894
Debian:14	cacti	1.2.31+ds1-1	DEBIAN-CVE-2026-39894
Ubuntu:24.04:LTS	cacti	no fix listed	UBUNTU-CVE-2026-39894
Ubuntu:25.10	cacti	no fix listed	UBUNTU-CVE-2026-39894
Ubuntu:26.04:LTS	cacti	no fix listed	UBUNTU-CVE-2026-39894
Ubuntu:26.10	cacti	no fix listed	UBUNTU-CVE-2026-39894

Affected products (as reported)

Vendor	Product	Versions
Cacti	cacti	< 1.2.31

Weakness: CWE-474 · Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

References

https://github.com/Cacti/cacti/security/advisories/GHSA-23g4-vf2j-94w4 x_refsource_CONFIRM
https://github.com/Cacti/cacti/issues/7011 x_refsource_MISC
https://github.com/Cacti/cacti/commit/d2a698854956e9e4e53da9eab5b5719ae40e6893 x_refsource_MISC