No VulnCrest analysis published for this CVE yet. Below is the original CNA/NVD description, unmodified.
Description
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.
Exploits & detection
No public PoC or detection template found yet.
Timeline
- Published: 30 Oct 2026
- Last modified upstream: 06 Nov 2026
Sources & licenses
- CVE / CVSS / CWE
- NVD record ↗ (unmodified). This product uses the NVD API but is not endorsed or certified by the NVD. CVE® © The MITRE Corporation.
- Exploitation
- CISA KEV (CC0) · EPSS by FIRST.org
- References used for the analysis
- https://github.com/litesaml/lightsaml/commit/230e62d1325f2cbcaac814b78409775f7a8806a2
- https://github.com/litesaml/lightsaml/commit/3af82bf2f3865e6aafeeb1a97c97b383b8bb7b00
- https://github.com/litesaml/lightsaml/pull/113
- https://github.com/litesaml/lightsaml/pull/122
- https://github.com/litesaml/lightsaml/releases/tag/4.7.1
- https://github.com/litesaml/lightsaml/releases/tag/5.0.1
- https://github.com/litesaml/lightsaml/security/advisories/GHSA-w553-pwx6-3mg9
- https://github.com/litesaml/lightsaml/security/advisories/GHSA-w553-pwx6-3mg9
- Analysis, summary and remediation
- © VulnCrest