Description
The SimpleSAMLphp SAML2 library is a PHP library for SAML2 related functionality. Prior to versions 4.17.0 and 5.0.0-alpha.20, there is a signature confusion attack in the HTTPRedirect binding. An attacker with any signed SAMLResponse via the HTTP-Redirect binding can cause the application to accept an unsigned message. Versions 4.17.0 and 5.0.0-alpha.20 contain a fix for the issue.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| simplesamlphp | saml2 | < 4.17.0, >= 5.0.0-alpha.1, < 5.0.0-alpha.20 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | simplesamlphp | 1.19.7-2 | — |
| Debian 12 | simplesamlphp | 1.19.7-1+deb12u2 | — |
| Debian 11 | simplesamlphp | 1.19.0-1+deb11u2 | DLA-4161-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 25.10 | simplesamlphp | No fix yet | — |
| Ubuntu 24.04 LTS | simplesamlphp | 1.19.7-1+deb12u1ubuntu0.1 | USN-8770-1 |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 22.04 LTS | simplesamlphp | 1.19.1-1.1ubuntu0.1~esm1 | USN-8770-1 |
| Ubuntu Pro 20.04 LTS | simplesamlphp | 1.18.4-1ubuntu0.1~esm1 | USN-8770-1 |
| Ubuntu Pro 18.04 LTS | simplesamlphp | 1.15.3-1ubuntu0.1~esm1 | USN-8770-1 |
| Ubuntu Pro 16.04 LTS | simplesamlphp | 1.14.0-1ubuntu2+esm1 | USN-8770-1 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Packagist | simplesamlphp/saml2 | < 4.17.0 | 4.17.0 | GHSA-46r4-f8gj-xg56 |
| Packagist | simplesamlphp/saml2 | >= 5.0.0-alpha.1, < 5.0.0-alpha.20 | 5.0.0-alpha.20 | GHSA-46r4-f8gj-xg56 |
| Packagist | simplesamlphp/saml2-legacy | < 4.17.0 | 4.17.0 | GHSA-46r4-f8gj-xg56 |
Advisories 2
- USN-8770-1 simplesamlphp vulnerabilities Ubuntu Security Notices (USN) · Sep 16, 2026
- DLA-4161-1 simplesamlphp - security update Debian Security (DSA / DLA) · Mar 9, 2026
References
- https://github.com/simplesamlphp/saml2/security/advisories/GHSA-46r4-f8gj-xg56
- https://github.com/simplesamlphp/saml2/commit/7867d6099dc7f31bed1ea10e5bea159c5623d2a0
- https://github.com/simplesamlphp/saml2/blob/9545abd0d9d48388f2fa00469c5c1e0294f0303e/src/SAML2/HTTPRedirect.php#L104-L113
- https://github.com/simplesamlphp/saml2/blob/9545abd0d9d48388f2fa00469c5c1e0294f0303e/src/SAML2/HTTPRedirect.php#L178-L217