CVE-2026-49283: SimpleSAMLphp saml2 authentication bypass via TLS validator confusion

CVE-2026-49283 · Severity: high · CVSS 8.7 · Published 2026-07-02

SimpleSAMLphp is a widely used tool for managing digital identities and single sign-on (SSO). A security flaw in how it handles certain login requests allows a malicious or lower-trust identity provider to impersonate users from a different, more trusted provider. This could allow an attacker to gain unauthorized access to sensitive corporate systems by forging user identities.

Technologies: simplesamlphp/saml2 (Packagist), simplesamlphp/saml2-legacy (Packagist). Vendors: Packagist, Simplesamlphp.

Quick answers

Is CVE-2026-49283 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-49283 being exploited in the wild.
How severe is CVE-2026-49283?
High severity, with a CVSS score of 8.7, published 2 July 2026.
Which products and versions are affected?
simplesamlphp/saml2 (Packagist) ECOSYSTEM:introduced=6.0.0,fixed=6.2.1; simplesamlphp/saml2-legacy (Packagist) ECOSYSTEM:introduced=4.20.0,fixed=4.20.2; Simplesamlphp Saml2 >= 6.0.0, < 6.2.1; >= 5.0.0, < 5.0.6; < 4.20.2; Simplesamlphp Saml2-Legacy < 4.20.2.
Is there a fix for CVE-2026-49283?
Yes. simplesamlphp/saml2 (Packagist): upgrade to 6.2.1 or later; simplesamlphp/saml2-legacy (Packagist): upgrade to 4.20.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-49283 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-49283?
Check whether you run simplesamlphp/saml2 (Packagist), simplesamlphp/saml2-legacy (Packagist), Simplesamlphp Saml2 or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • simplesamlphp/saml2 (Packagist): upgrade to 6.2.1 or later
    composer require simplesamlphp/saml2:^6.2.1
  • simplesamlphp/saml2-legacy (Packagist): upgrade to 4.20.2 or later
    composer require simplesamlphp/saml2-legacy:^4.20.2

Technical details

A vulnerability exists in the HTTP-Artifact receive path of SimpleSAMLphp where TLS validator confusion occurs. In the `HTTPArtifact::receive()` flow, the `SOAPClient::validateSSL()` method fails to throw an exception when a TLS public key mismatch occurs, returning normally instead. Because `SAML2\Message::validate()` interprets any non-exception return as a successful validation, an unsigned SAML Response embedded in a SOAP ArtifactResponse from one IdP can be incorrectly validated against the metadata of a different IdP. This allows a malicious IdP to mint assertions for arbitrary users belonging to a higher-trust IdP within the same federation. The issue is patched in versions 6.2.1, 5.0.6, and 4.20.2.

Affected products

  • SimpleSAMLphp saml2 >= 6.0.0, < 6.2.1; >= 5.0.0, < 5.0.6; < 4.20.2
  • SimpleSAMLphp saml2-legacy < 4.20.2

Identifiers

  • CVE-2026-49283
  • GHSA-6929-8p9f-26jx

Timeline

  • 2026-05-29: disclosed
  • 2026-07-02: advisory

References

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