Medium (5.4) in syguestbook a5 project syguestbook a5. EPSS 0.7% chance of exploitation in the next 30 days.
SyGuestBook A5 Version 1.2 allows stored XSS because the isValidData function in include/functions.php does not properly block XSS payloads, as demonstrated by a crafted use of the onerror attribute of an IMG element.
Severity
CVSS 3.0
5.4 medium
CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
EPSS
0.7% chance of exploitation in the next 30 days; higher than 53% of CVEs (scores of 2026-10-31)