XSS in S9y Serendipity
CVE-2026-73628
Serendipity versions >= 2.3.5 and <= 2.6.0 contain a reflected cross-site scripting vulnerability in the search clean-URL route (/search/<term>). In include/functions_routing.inc.php serveSearch(), the sanitisation pipeline runs urldecode() after HTML-encoding, so a single URL-encoded HTML payload survives strip_tags() and htmlspecialchars() and is then decoded back into live HTML in the page. A crafted search link can execute arbitrary JavaScript in the victim's browser. Fixed in 2.6.1.
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.003 (16.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 16th percentile — 16.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001
Affected products
- S9y Serendipity — versions 0
Weakness classification (CWE)
References
- github.com/s9y/Serendipity/security/advisories/GHSA-6c2x-mjmq-vx4q (vendor-advisory)
- www.vulncheck.com/advisories/serendipity-reflected-xss-via-search-clean-url-rou… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-73628?
- CVE-2026-73628 is a medium-severity vulnerability in S9y Serendipity, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-08-13.
- How severe is CVE-2026-73628?
- Medium severity. CVSS v3 base score is 6.1 out of 10.