Vulnerability · Published Aug 13, 2026 · Assigned by VulnCheck

CVE-2026-73629Serendipity before 2.6.0 SSRF via hex IPv4 and IPv6 addresses

High 8.5

In plain English

A high-severity server-side request forgery in Serendipity from s9y. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 25% of all known vulnerabilities).

Severity (CVSS 3.1)8.5High

Exploit odds (30 days)0.3%top 74.9% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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.

Affected products (as reported)

Vendor	Product	Versions
s9y	Serendipity	0 – before 2.6.0

Weakness: CWE-918 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N

References

GitHub Security Advisory (GHSA-2m48-gjj5-5x86) vendor-advisory
VulnCheck Advisory: Serendipity before 2.6.0 SSRF via hex IPv4 and IPv6 addresses third-party-advisory