CVE-2026-63182 (GCVE-0-2026-63182)

Vulnerability from cvelistv5 – Published: 2026-10-30 21:46 – Updated: 2026-10-30 21:46
VLAI
Title
LightSAML: Signature reference wrapping permits unsigned assertion claims
Summary
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.
Severity
8.1 (High)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
CWE
  • CWE-347 - Improper Verification of Cryptographic Signature
Assigner
GitHub_M CNA under the mitre root
CNA scorecard C 72/100 over 7886 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
litesaml lightsaml Affected: < 4.7.1
Affected: >= 5.0.0, < 5.0.1
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

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          "vendor": "litesaml",
          "versions": [
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              "status": "affected",
              "version": "\u003c 4.7.1"
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              "version": "\u003e= 5.0.0, \u003c 5.0.1"
            }
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          "value": "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."
        }
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      "metrics": [
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          "url": "https://github.com/litesaml/lightsaml/security/advisories/GHSA-w553-pwx6-3mg9"
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        },
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          "tags": [
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          "url": "https://github.com/litesaml/lightsaml/releases/tag/4.7.1"
        },
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          "tags": [
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          "url": "https://github.com/litesaml/lightsaml/releases/tag/5.0.1"
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      "source": {
        "advisory": "GHSA-w553-pwx6-3mg9",
        "discovery": "UNKNOWN"
      },
      "title": "LightSAML: Signature reference wrapping permits unsigned assertion claims"
    }
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    "datePublished": "2026-10-30T21:46:38.551Z",
    "dateReserved": "2026-07-15T22:13:00.721Z",
    "dateUpdated": "2026-10-30T21:46:38.551Z",
    "state": "PUBLISHED"
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                "product": "lightsaml",
                "vendor": "litesaml",
                "versions": [
                  {
                    "status": "affected",
                    "version": "\u003c 4.7.1"
                  },
                  {
                    "status": "affected",
                    "version": "\u003e= 5.0.0, \u003c 5.0.1"
                  }
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            "source": "security-advisories@github.com"
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            "value": "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."
          }
        ],
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        "lastModified": "2026-11-02T19:34:23.993",
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            "source": "security-advisories@github.com",
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            "source": "security-advisories@github.com",
            "type": "Primary"
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    }
  }
}



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