جزئیات آسیب‌پذیری

LightSAML implements SAML 2.0 data model classes, XML serialization and deserialization, XML security, certificate support, and message bindings. Prior to 4.7.1 and 5.0.1, LightSAML and xmlseclibs disagree about which assertion an inbound SAML signature covers. `Response::deserialize` uses `manyElementsFromXml` to collect only direct-child `saml:Assertion` elements of `samlp:Response`, and `AssertionSignatureValidatorAction` validates their `ds:Signature` using an out-of-band trusted IdP credential resolved by Issuer, not a key from the document. `XMLSecurityDSig::validateReference()` removes the enveloped signature from the shared DOM, but `processRefNode()` resolves `Reference URI="#id"` document-wide through an XPath of the form `//*[@Id]` and takes `item(0)`, which need not be the assertion whose claims LightSAML consumes. An attacker who has captured one genuinely signed assertion, such as an earlier login response, can place its signature-stripped bytes earlier in `samlp:Extensions` and present a forged direct-child assertion with the same ID and copied genuine signature. Validation then covers the hidden genuine bytes while LightSAML surfaces unsigned attacker-controlled `Subject/NameID`, `Conditions`, and `Attributes`, enabling authentication bypass or privilege escalation even when signature validation is required. The behavior was confirmed in versions 5.0.0 and 4.6.1. This issue is fixed in versions 4.7.1 and 5.0.1.

• https://github.com/litesaml/lightsaml/pull/113 x_refsource_MISC
• https://github.com/litesaml/lightsaml/pull/122 x_refsource_MISC
• https://github.com/litesaml/lightsaml/commit/230e62d1325f2cbcaac814b78409775f7a8806a2 x_refsource_MISC
• https://github.com/litesaml/lightsaml/commit/3af82bf2f3865e6aafeeb1a97c97b383b8bb7b00 x_refsource_MISC
• https://github.com/litesaml/lightsaml/releases/tag/4.7.1 x_refsource_MISC
• https://github.com/litesaml/lightsaml/releases/tag/5.0.1 x_refsource_MISC
• https://github.com/litesaml/lightsaml/security/advisories/GHSA-w553-pwx6-3mg9 x_refsource_CONFIRM