CVE-2026-49284 is a high-severity security vulnerability in simplesamlphp/simplesamlphp (composer), affecting versions >= 2.5.0, <= 2.5.1. It is fixed in 2.5.2, 2.4.7.
Summary SimpleSAMLphp's SAML SP ACS path does not enforce the IdP selected for an SP-initiated login. If a saved SP state contains ExpectedIssuer = IdP A, but the ACS receives a valid response from IdP B, the code logs a warning and continues processing instead of rejecting the response. That behavior becomes security-relevant when combined with the response-processing rule that accepts an unsigned samlp:Response/@InResponseTo outside the signed assertion whenever the signed assertion's SubjectConfirmationData does not carry its own InResponseTo. A response issued by one trusted IdP can therefore be bound to SP state created for another IdP. Impact In a multi-IdP deployment, a lower-trust IdP can satisfy SP state created for a different expected IdP. This can bypass an SP flow that intentionally routes the user to a specific IdP, including deployments that set enable_unsolicited to false to prevent IdP-initiated logins. The impact is highest when the SP trusts multiple IdPs with different assurance levels, tenant boundaries, or attribute namespaces, and application authorization depends on the selected/expected IdP. In those deployments this is an authentication/authorization bypass candidate. Impact strongly depends on whether an attacker can obtain a signed IdP-initiated assertion from a lower-trust trusted IdP and whether the downstream application maps identifiers globally.
CVE-2026-49284 has a CVSS score of 7.1 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment.
A fixed version is available (2.5.2, 2.4.7). Upgrading removes the vulnerable code path.
composer
simplesamlphp/simplesamlphp (>= 2.5.0, <= 2.5.1)simplesamlphp/simplesamlphp (<= 2.4.6)simplesamlphp/simplesamlphp → 2.5.2 (composer)simplesamlphp/simplesamlphp → 2.4.7 (composer)Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter instead of chasing every advisory.
Kodem's runtime-powered SCA identifies whether CVE-2026-49284 is reachable in your applications. Explore open-source security for your team.
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Already deployed Kodem? See CVE-2026-49284 in your environment →Upgrade the following packages to resolve this vulnerability:
simplesamlphp/simplesamlphp to 2.5.2 or latersimplesamlphp/simplesamlphp to 2.4.7 or laterKodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
CVE-2026-49284 is a high-severity security vulnerability in simplesamlphp/simplesamlphp (composer), affecting versions >= 2.5.0, <= 2.5.1. It is fixed in 2.5.2, 2.4.7.
CVE-2026-49284 has a CVSS score of 7.1 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
simplesamlphp/simplesamlphp (composer) versions >= 2.5.0, <= 2.5.1 is affected.
Yes. CVE-2026-49284 is fixed in 2.5.2, 2.4.7. Upgrade to this version or later.
Whether CVE-2026-49284 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
simplesamlphp/simplesamlphp to 2.5.2 or latersimplesamlphp/simplesamlphp to 2.4.7 or later