SSRF in S9y Serendipity
CVE-2026-73629
Serendipity before 2.6.0 contains a server-side request forgery vulnerability in the serendipity_url_allowed() filter that fails to block hex-encoded IPv4 addresses, IPv6 literals, and link-local ranges. Authenticated users with adminImagesAdd permission can bypass the filter using alternate address formats to request internal services and retrieve response bodies through the public uploads directory.
Vulnerability class: SSRF (Server-Side Request Forgery)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N.
EPSS exploit prediction
EPSS: 0.003 (22.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 22nd percentile — 22.4% 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, 2.6.0
Weakness classification (CWE)
References
- github.com/s9y/Serendipity/security/advisories/GHSA-2m48-gjj5-5x86 (vendor-advisory)
- www.vulncheck.com/advisories/serendipity-before-ssrf-via-hex-ipv4-and-ipv6-addr… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-73629?
- CVE-2026-73629 is a high-severity vulnerability in S9y Serendipity, classified under Server-Side Request Forgery (SSRF). CVSS score: 8.5/10. Published 2026-08-13.
- How severe is CVE-2026-73629?
- High severity. CVSS v3 base score is 8.5 out of 10.