---
title: "CVE-2025-24894: The AspNetCore Remote Authenticator for SPID Allows SAML Response Signature Verification Bypass"
url: https://erroneo.us/security/cve/CVE-2025-24894/
description: "CVE-2025-24894 (SPID.AspNetCore.Authentication (NuGet)): SPID.AspNetCore.Authentication is an AspNetCore Remote Authenticator for SPID. Authentication using…"
type: vulnerability-record
section: "Security Digest"
date_published: 2025-02-18
date_modified: 2025-02-18
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2025-24894"
kev: false
cvss: 9.1
epss: 0.00607
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2025-24894: The AspNetCore Remote Authenticator for SPID Allows SAML Response Signature Verification Bypass

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.6% , percentile 48: FIRST’s model estimates a 0.6% chance of exploitation activity in the next 30 days, higher than 48% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes SPID.AspNetCore.Authentication (NuGet) <= 3.3.0, fixed in 3.4.0 . Check your lockfile, including transitive dependencies.

## What it is

SPID.AspNetCore.Authentication is an AspNetCore Remote Authenticator for SPID. Authentication using Spid and CIE is based on the SAML2 standard which provides two entities: Identity Provider (IDP): the system that authenticates users and provides identity information (SAML affirmation) to the Service Provider, in essence, is responsible for the management of the credentials and identity of users; Service Provider (SP): the system that provides a service to the user and relies on the Identity Provider to authenticate the user, receives SAML assertions from the IdP to grant access to resources. The validation logic of the signature is central as it ensures that you cannot create a SAML response with arbitrary assertions and then impersonate other users. There is no guarantee that the first signature refers to the root object, it follows that if an attacker injects an item signed as the first element, all other signatures will not be verified. The only requirement is to have an XML element legitimately signed by the IdP, a condition that is easily met using the IdP's public metadata. An attacker could create an arbitrary SAML response that would be accepted by SPs using vulnerable SDKs, allowing him to impersonate any Spid and/or CIE user. This vulnerability has been addressed in version 3.4.0 and all users are advised to upgrade. There are no known workarounds for this vulnerability.

## Affected packages

- NuGet `SPID.AspNetCore.Authentication` <= 3.3.0 → fixed: 3.4.0

## Affected products (CVE record)

- italia spid-aspnetcore: < 3.4.0

## Severity

- GitHub_M CVSS 3.1: 9.1 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`
- GitHub CVSS 3.1: 9.1 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.61% probability of exploitation activity in the next 30 days; percentile 48.

## Sources

- [GitHub Advisory GHSA-36h8-r92j-w9vw](https://github.com/advisories/GHSA-36h8-r92j-w9vw)
- [CVE.org record CVE-2025-24894](https://www.cve.org/CVERecord?id=CVE-2025-24894)
- [NVD entry CVE-2025-24894](https://nvd.nist.gov/vuln/detail/CVE-2025-24894)
- [github.com](https://github.com/italia/spid-aspnetcore/security/advisories/GHSA-36h8-r92j-w9vw)
- [github.com](https://github.com/italia/spid-aspnetcore/commit/093efa2273f8a1e0481f678a0bfcd57fbdc7b029)

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Source page: https://erroneo.us/security/cve/CVE-2025-24894/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt