Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
SimpleSAMLphp versions below 2.4.7 and from 2.5.0 up to (not including) 2.5.2 are affected. When a saved SP login state expects one identity provider but the assertion consumer service accepts a valid response from a different trusted IdP, the SP only logs a warning and continues, and an unsigned InResponseTo attribute can be accepted for that response. An attacker who controls or can obtain a signed assertion from a lower-trust trusted IdP could therefore bypass a flow meant to route users to a specific IdP, which matters most in multi-IdP deployments. Upgrade to 2.4.7 or 2.5.2.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 7.1 | High | 3.1 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N | CNA (GitHub_M) |
- CISA KEV Not listed.
- EPSS 0.0022, the 12th percentile, on 9 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 14:00 UTC First seen by agentprime
- 31 Oct 2026, 14:00 UTC Confirmed by OSV