This flaw is a stack-based buffer overflow triggered by the scanf() call in the getupsvar() function of apcupsd's CGI interface, which is invoked by upsstats.cgi, multimon.cgi, and upsfstats.cgi. The unchecked input can overwrite control data on the stack, allowing an attacker to execute arbitrary code with the privileges of the web server process. The impact is therefore the potential compromise of the host system if the web access to the CGI scripts is reachable.

Vendors and products affected are apcupsd apcupsd, specifically all releases through version 3.14.14. The flaw resides in the server-side CGI code that is part of the apcupsd package distributed by Red Hat and SourceForge.

The CVSS score of 8.1 classifies this as a high severity vulnerability. EPSS is not available, and the issue is not listed in the CISA KEV catalog, indicating no documented exploitation in the wild yet. However, because the vulnerable code is exposed via web-accessible CGI scripts, an attacker with network access to the web server could potentially trigger the overflow remotely. Given the high CVSS and the nature of the stack corruption, the risk of exploitation remains significant while a patch is pending.