SimpleSAMLphp-casserver has an Open Redirect vulnerability via logout

published 2026-05-15 5 mo ago modified 2026-10-07 33 d ago also GHSA-cvrm-5hp6-h523 , EUVD-2025-209889

cvss: 4.7; version 3.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 19%
public exploits: 0; none known

SimpleSAMLphp-casserver is a CAS 1.0 and 2.0 compliant CAS server in the form of a SimpleSAMLphp module. In versions below 6.3.1 and 7.0.0, the logout endpoint accepts a url query parameter to redirect to. casserver treats that url as trusted, and either (depending on configuration) redirects the browser there, or shows a "you've been logged out" page with a link to continue to that url. Impacted configs include 'enable_logout' => true, and 'skip_logout_page' -> true. This issue has been resolved in versions 6.3.1 and 7.0.0.

Patch / fix

fixed in 2 links 2

packagist simplesamlphp/simplesamlphp-module-casserver 6.3.1, 7.0.0
simplesamlphp simplesamlphp-module-casserver 6.3.1

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 5 mo ago (2026-05-18)

Exploit prediction

0.27% chance of exploitation in the next 30 days, higher than 19% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/simplesamlphp/simplesamlphp-module-casserver/security/advisories/GHSA-cvrm-5hp6-h523 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.0	4.7	CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
NVD	3.1	6.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
GitHub	3.0	4.7	CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N

Affected packages

ecosystem	package	affected	fixed in
packagist	simplesamlphp/simplesamlphp-module-casserver	>=7.0.0-rc1, <7.0.0 <6.3.1	7.0.0 6.3.1

Affected products

simplesamlphp simplesamlphp-module-casserver

Classification

Weakness

CWE-601 URL Redirection to Untrusted Site

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary