CVE-2026-39894
Cacti: RRDtool metric shift via LC_NUMERIC locale comma decimal formatting
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.
INFO
Published Date :
June 24, 2026, 10:16 p.m.
Last Modified :
June 25, 2026, 8:19 p.m.
Remotely Exploit :
No
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | LOW | [email protected] | ||||
| CVSS 3.1 | LOW | [email protected] |
Solution
- Update Cacti to version 1.2.31 or later.
- Ensure server locale uses period as decimal separator.
- Monitor RRDtool metric data integrity.
Public PoC/Exploit Available at Github
CVE-2026-39894 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-39894.
| URL | Resource |
|---|---|
| https://github.com/Cacti/cacti/commit/d2a698854956e9e4e53da9eab5b5719ae40e6893 | Patch |
| https://github.com/Cacti/cacti/issues/7011 | Issue Tracking Patch |
| https://github.com/Cacti/cacti/security/advisories/GHSA-23g4-vf2j-94w4 | Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-39894 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-39894
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
None
Ruby PHP HTML CSS JavaScript Less SCSS Shell Perl Dockerfile
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-39894 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-39894 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Jun. 25, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N Added CPE Configuration OR *cpe:2.3:a:cacti:cacti:*:*:*:*:*:*:*:* versions up to (excluding) 1.2.31 Added Reference Type GitHub, Inc.: https://github.com/Cacti/cacti/commit/d2a698854956e9e4e53da9eab5b5719ae40e6893 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/Cacti/cacti/issues/7011 Types: Issue Tracking, Patch Added Reference Type GitHub, Inc.: https://github.com/Cacti/cacti/security/advisories/GHSA-23g4-vf2j-94w4 Types: Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 25, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-39894', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-06-25T13:02:29.458961Z'} -
New CVE Received by [email protected]
Jun. 24, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'Cacti', 'product': 'cacti', 'versions': [{'status': 'affected', 'version': '< 1.2.31'}]}] Added 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. Added CVSS V3.1 AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N Added CWE CWE-474 Added Reference https://github.com/Cacti/cacti/commit/d2a698854956e9e4e53da9eab5b5719ae40e6893 Added Reference https://github.com/Cacti/cacti/issues/7011 Added Reference https://github.com/Cacti/cacti/security/advisories/GHSA-23g4-vf2j-94w4