CVE-2017-18122

Severity: high (CVSS 8.1 v3.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2018-02-02 · updated 2026-06-17
Weakness: CWE-347

Description

A signature-validation bypass issue was discovered in SimpleSAMLphp through 1.14.16. A SimpleSAMLphp Service Provider using SAML 1.1 will regard as valid any unsigned SAML response containing more than one signed assertion, provided that the signature of at least one of the assertions is valid. Attributes contained in all the assertions received will be merged and the entityID of the first assertion received will be used, allowing an attacker to impersonate any user of any IdP given an assertion signed by the targeted IdP.

Affected products

Debian Linux: 7.0, 8.0, 9.0
simplesamlphp: through 1.14.16

References

https://lists.debian.org/debian-lts-announce/2018/02/msg00008.html
https://simplesamlphp.org/security/201710-01
https://www.debian.org/security/2018/dsa-4127
https://lists.debian.org/debian-lts-announce/2018/02/msg00008.html
https://simplesamlphp.org/security/201710-01
https://www.debian.org/security/2018/dsa-4127

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