{"id":"CVE-2026-87947","kind":"vulnerability","aliases":["CVE-2026-87947"],"related":[],"title":"Drupal SAML SSO Service Provider: signature checks can be spoofed","description":"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.","summary":"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.","severity":"medium","cvss":4.8,"epss":0.00113,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["drupal","package","saml","self-hosted","sso"],"not_affected_if":["module-not-installed","saml-sso-not-used"],"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`\n- unknown whether any other check is available","fix":"- Upgrade the SAML SSO - Service Provider module to a version later than `3.2.0`\n- unknown which exact fixed version is available from the sources","status":"open","published_at":"2026-10-22T02:17:04+00:00","first_seen_at":"2026-10-23T21:57:30+00:00","triaged_at":"2026-10-25T04:33:06+00:00","updated_at":"2026-10-25T04:33:06+00:00","category":"package","confidence":0.5,"triage":{"at":"2026-10-25T04:33:06Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade the SAML SSO - Service Provider module to a version later than `3.2.0`\n- unknown which exact fixed version is available from the sources","reach":"internet","title":"Drupal SAML SSO Service Provider: signature checks can be spoofed","impact":"high","summary":"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.","category":"package","nicknames":[],"who_cares":["drupal","saml","sso","self-hosted"],"confidence":0.5,"needs_auth":"unknown","worst_case":"Attacker forges SAML login responses and signs in as other users","analyst_note":"Confirm the fixed version and whether the flaw allows full account takeover; check the NVD entry at https://nvd.nist.gov/vuln/detail/CVE-2026-87947 for details.","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`\n- unknown whether any other check is available","needs_analyst":true,"not_affected_if":["module-not-installed","saml-sso-not-used"],"who_is_affected":"Sites running the Drupal SAML SSO - Service Provider module at version 3.2.0 or earlier that use it for single sign-on. Sites that do not use SAML single sign-on through this module are not affected.","user_interaction":"unknown","needs_special_setup":"yes","severity_if_unknown":"unknown"},"cost_usd":0.000623,"input_tokens":3347,"output_tokens":577,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-2026':12A,15A '-87947':13A,16A '0.0.0':94C '3.2.0':96C 'abl':54B 'affect':87C 'allow':38B,82C 'anoth':59B 'attack':42B 'check':7A 'cryptograph':73C 'cve':11A,14A 'drupal':1A,17B,25B,77C 'exact':68B 'forg':45B 'host':22B 'improp':70C 'issu':86C 'log':56B 'look':49B 'may':52B 'modul':30B 'outcom':69B 'packag':18B 'proper':33B 'provid':5A,29B,81C,91C 'respons':36B,51B 'saml':2A,19B,26B,35B,50B,78C,88C 'self':21B 'self-host':20B 'servic':4A,28B,80C,90C 'sign':48B 'signatur':6A,37B,39B,74C,83C 'signed-look':47B 'sourc':63B 'spoof':10A,40B,84C 'sso':3A,23B,27B,79C,89C 'state':66B 'though':61B 'user':60B 'verif':71C 'verifi':34B 'version':92C 'vulner':75C","nicknames":[],"mitigations":[],"who_affected":"Sites running the Drupal SAML SSO - Service Provider module at version 3.2.0 or earlier that use it for single sign-on. Sites that do not use SAML single sign-on through this module are not affected.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-22T02:17:04+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","cvss_by":"134c704f-9b21-4f2e-91b3-4a467353bcc0","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-87947","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-87947","severity":null,"published_at":"2026-10-22T02:17:04+00:00","modified_at":"2026-10-22T17:17:00+00:00","first_seen_at":"2026-10-23T21:57:30+00:00","fetched_at":"2026-10-23T22:29:02+00:00","note":null},{"source":"epss","external_id":"CVE-2026-87947","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-87947","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-24T07:15:52+00:00","fetched_at":"2026-10-24T07:15:52+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}