{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata. Fed continuously.","feed_url":"https://feed.craftedsignal.io/vendors/edumfa/feed.json","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cpes":[],"_cs_cves":[],"_cs_exploited":false,"_cs_has_poc":false,"_cs_poc_references":[],"_cs_products":["eduMFA (\u003c 2.9.1)"],"_cs_severities":["high"],"_cs_tags":["replay-attack","authentication","webauthn"],"_cs_type":"advisory","_cs_vendors":["eduMFA"],"content_html":"\u003cp\u003eeduMFA versions prior to 2.9.1 are susceptible to a replay attack vulnerability affecting userless Passkey/WebAuthn authentication. This flaw stems from the absence of an expiration flag within the challenge generated during the authentication process. Consequently, an attacker could potentially capture a valid, unexpired challenge and reuse it to bypass authentication, even after the legitimate user\u0026rsquo;s session has ended or the challenge should have expired. This issue was addressed in eduMFA version 2.9.1 by implementing validity information for userless challenges. Defenders should prioritize upgrading vulnerable instances of eduMFA to version 2.9.1 or later to mitigate this risk.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eUser initiates a userless Passkey/WebAuthn authentication request against an eduMFA instance running a version prior to 2.9.1.\u003c/li\u003e\n\u003cli\u003eeduMFA generates a challenge without proper expiration or validity constraints.\u003c/li\u003e\n\u003cli\u003eAttacker intercepts the challenge during transmission or retrieves it from a compromised system.\u003c/li\u003e\n\u003cli\u003eThe legitimate user completes the authentication, granting access to protected resources.\u003c/li\u003e\n\u003cli\u003eAttacker replays the previously intercepted challenge to the eduMFA instance.\u003c/li\u003e\n\u003cli\u003eDue to the missing expiration check, eduMFA incorrectly validates the replayed challenge as legitimate.\u003c/li\u003e\n\u003cli\u003eAttacker gains unauthorized access to the protected resources, impersonating the original user.\u003c/li\u003e\n\u003cli\u003eAttacker performs actions within the system using the compromised session, potentially escalating privileges or exfiltrating sensitive data.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation of this vulnerability allows attackers to bypass multi-factor authentication and gain unauthorized access to systems and data protected by eduMFA. This can lead to data breaches, financial losses, and reputational damage. The impact is significant as it undermines the security guarantees provided by multi-factor authentication, especially in environments relying on userless Passkey/WebAuthn authentication.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eUpgrade all eduMFA installations to version 2.9.1 or later to remediate the vulnerability as described in the overview.\u003c/li\u003e\n\u003cli\u003eDeploy the Sigma rule \u0026ldquo;Detect eduMFA Passkey Replay Attempt\u0026rdquo; to identify potential replay attacks by monitoring for multiple authentication attempts using the same challenge.\u003c/li\u003e\n\u003cli\u003eIf immediate patching is not possible, consider temporarily disabling userless login as suggested in the advisory.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2026-05-18T15:37:32Z","date_published":"2026-05-18T15:37:32Z","id":"https://feed.craftedsignal.io/briefs/2026-05-edumfa-passkey-replay/","summary":"eduMFA versions prior to 2.9.1 are vulnerable to replay attacks due to a missing expiration flag in userless Passkey/WebAuthn challenges, potentially leading to unauthorized access.","title":"eduMFA Passkey Replay Vulnerability","url":"https://feed.craftedsignal.io/briefs/2026-05-edumfa-passkey-replay/"}],"language":"en","title":"CraftedSignal Threat Feed — EduMFA","version":"https://jsonfeed.org/version/1.1"}