---
id: "CVE-2026-87947"
kind: "vulnerability"
aliases: ["CVE-2026-87947"]
title: "Drupal SAML SSO Service Provider: signature checks can be spoofed"
severity: "medium"
cvss: 4.8
epss: 0.00113
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["drupal", "package", "saml", "self-hosted", "sso"]
not_affected_if: ["module-not-installed", "saml-sso-not-used"]
published_at: "2026-10-22T02:17:04+00:00"
first_seen_at: "2026-10-23T21:57:30+00:00"
updated_at: "2026-10-25T04:33:06+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-87947", "first_seen_at": "2026-10-23T21:57:30+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-87947", "first_seen_at": "2026-10-24T07:15:52+00:00"}]
---

# Drupal SAML SSO Service Provider: signature checks can be spoofed

The Drupal SAML SSO - Service Provider module does not properly verify SAML response signatures, allowing signature spoofing. An attacker who can forge a signed-looking SAML response may be able to log in as another user, though the sources do not state the exact outcome.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed version of the Drupal SAML SSO - Service Provider module with `drush pm:list --filter=saml` or by reviewing `composer show drupal/saml`
- unknown whether any other check is available

## Fix

- Upgrade the SAML SSO - Service Provider module to a version later than `3.2.0`
- unknown which exact fixed version is available from the sources

## Timeline

- 2026-10-23T21:57:30+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-87947
- 2026-10-24T07:15:52+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-87947

## From the sources

Improper Verification of Cryptographic Signature vulnerability in Drupal SAML SSO - Service Provider  allows Signature Spoof. This issue affects SAML SSO - Service Provider  versions: from 0.0.0 to 3.2.0.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_