Vulnerability · Published Jul 17, 2026 · Assigned by GitHub_M
CVE-2026-49284SimpleSAMLphp SP accepts a response from an unexpected IdP when unsigned `Response/InResponseTo` is combined with a signed assertion lacking `SubjectConfirmationData/InResponseTo`
High 7.1
In plain English
A high-severity insufficient verification of data authenticity in simplesamlphp from simplesamlphp. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 13% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
SimpleSAMLphp versions before 1.18.6 contain an information disclosure vulnerability. Prior to 2.4.7 and 2.5.2, SimpleSAMLphp's SAML SP ACS path does not enforce the IdP selected for an SP-initiated login when unsigned Response/InResponseTo is combined with a signed assertion lacking SubjectConfirmationData/InResponseTo, allowing a response issued by one trusted IdP to be bound to SP state created for another IdP and bypass flows that route users to a specific IdP, including deployments that set enable_unsolicited to false. This issue is fixed in versions 2.4.7 and 2.5.2.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | simplesamlphp | no fix listed | DEBIAN-CVE-2026-49284 |
| Debian:14 | simplesamlphp | 2.4.8-1 | DEBIAN-CVE-2026-49284 |
| Packagist | simplesamlphp/simplesamlphp | 2.4.7 | GHSA-q8r6-xj3f-wrrm |
| Packagist | simplesamlphp/simplesamlphp | 2.5.2 | GHSA-q8r6-xj3f-wrrm |
| Ubuntu:24.04:LTS | simplesamlphp | no fix listed | UBUNTU-CVE-2026-49284 |
| Ubuntu:26.04:LTS | simplesamlphp | no fix listed | UBUNTU-CVE-2026-49284 |
| Ubuntu:26.10 | simplesamlphp | no fix listed | UBUNTU-CVE-2026-49284 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| simplesamlphp | simplesamlphp | < 2.4.7>= 2.5.0-rc1, < 2.5.2 |
Weakness: CWE-345 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N