# The AspNetCore Remote Authenticator for SPID Allows SAML Response Signature Verification Bypass

Advisory record · `GHSA-36h8-r92j-w9vw`

- **Identifiers:** `GHSA-36h8-r92j-w9vw` · `CVE-2025-24894`
- **State:** Confirmed
- **Severity:** CVSS 9.1 Critical
- **Critical:** Yes: CVSS 9+
- **Weakness (CWE):** [CWE-287](https://cwe.mitre.org/data/definitions/287.html) · [CWE-290](https://cwe.mitre.org/data/definitions/290.html)
- **Tags:** [Authentication bypass](https://agentprime.io/advisories/tag/auth-bypass.md)
- **Published:** 18 Feb 2025
- **Updated:** 18 Feb 2025
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 18 Feb 2025, 19:25 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Critical

Critical, because:

- CVSS score 9.1: 9.0 or more.

How we decide what’s critical: <https://agentprime.io/advisories/critical.md>

## Affected packages

- `SPID.AspNetCore.Authentication` (NuGet): affected `<3.4.0`; fixed in `3.4.0`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> NuGet package SPID.AspNetCore.Authentication versions before 3.4.0 are affected. The library does not verify all signatures in a SAML response, only the first one found, so an attacker who can supply an element carrying a valid signature from a configured identity provider (obtainable from public metadata) can craft a response with arbitrary assertions and impersonate any SPID or CIE user. Upgrade to version 3.4.0 or later.

Written 9 Nov 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 9.1 Critical, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0061, the 49th percentile, on 11 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 15:22 UTC: First seen by agentprime
- 31 Oct 2026, 15:22 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-36h8-r92j-w9vw)

## Sources

- [GitHub Advisory Database: GHSA-36h8-r92j-w9vw](https://github.com/advisories/GHSA-36h8-r92j-w9vw)
- [OSV: GHSA-36h8-r92j-w9vw](https://osv.dev/vulnerability/GHSA-36h8-r92j-w9vw)
- <https://github.com/italia/spid-aspnetcore/security/advisories/GHSA-36h8-r92j-w9vw>
- <https://github.com/italia/spid-aspnetcore/commit/093efa2273f8a1e0481f678a0bfcd57fbdc7b029>
- <https://github.com/italia/spid-aspnetcore>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-36h8-r92j-w9vw>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-36h8-r92j-w9vw/>. Everything for agents: <https://agentprime.io/llms.txt>.