EUVD-2026-86276Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
-
AccessObtain valid signed assertion for another SP
-
DeliveryReach authentik SAML Source ACS endpoint
-
ExploitSubmit unaddressed or previously-used assertion
-
ExecutionSignature/validity pass, no audience or replay check
-
ImpactAuthenticate as named user
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A07:2025 - Authentication Failures
ASVS 5.0
V6 - Authentication Authentication mechanism validation
MITRE ATT&CK
2 techniques across 2 tactics: Defense Evasion, Initial Access The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | Exploitation requires that the target deployment uses an authentik SAML Source (SP-side federation) running a version prior to 2026.2.7 / 2026.5.7 / 2026.8.2; SAML Providers and all other Source types are explicitly unaffected. The attacker must possess a validly-signed, unexpired assertion from the IdP the Source trusts - obtained either as an assertion the IdP issued for a different service provider (exploiting the missing audience/Destination/Recipient binding) or as a previously-issued assertion captured for replay (exploiting the absence of consumed-assertion tracking). No credentials or user interaction are needed on the authentik side (PR:N/UI:N), but the dependence on sourcing a valid pre-existing assertion is the primary limiting factor and the basis for AC:H. |
| Impact | This is a genuine high-priority authentication flaw despite the absence of active-exploitation signals. The provided CVSS 3.1 vector (AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N, base 7.4) is well-supported by the description and the patch diff: an unauthenticated network attacker (PR:N) who holds a validly-signed SAML assertion can authenticate as the named user, yielding full account takeover (C:H/I:H). The AC:H rating is justified because the attacker must first obtain a valid, correctly-signed assertion issued by the same IdP - either one minted for a different service provider (an audience/recipient confusion attack) or a previously-captured assertion replayed within its validity window - which is a real precondition beyond the attacker's direct control. No EPSS score, no CISA KEV listing, and no public POC are present in the input, so there is no evidence of exploitation in the wild; this is a patch-driven advisory reported through GitHub. However, the vulnerability class (SAML audience/recipient binding failure plus missing replay protection) is well-understood, the fix is public across three release branches, and the code diff itself functions as a roadmap, so the practical exploitability once an attacker can source an assertion is meaningful. No SSVC decision data was provided. Net: real security-relevant issue in an identity provider - treat as elevated priority for authentik operators using SAML Sources - but currently theoretical rather than observed. |
| Exploit ScenarioDerived | An organization uses authentik as an SP-side SAML Source federating to an external IdP that also issues assertions to other service providers. An attacker who legitimately obtains (or intercepts) a bearer assertion the IdP issued for a different service provider - or captures a user's earlier assertion - submits it to the authentik SAML Source ACS endpoint. Because authentik checks only the signature and validity period, not that the assertion was addressed to this Source or issued in response to its request, and never records consumed assertion IDs, the attacker is logged in as the user named in the assertion. No public POC was identified at time of analysis. |
Get an e-mail when this CVE is exploited, patched or re-scored. Free account.
Alert meAnalysisAIv1 – Sep 24, 2026
Authentication bypass in authentik's SAML Source lets an unauthenticated attacker who holds any validly-signed, unexpired SAML assertion from a trusted identity provider log in as the user named in that assertion, because releases before 2026.2.7, 2026.5.7, and 2026.8.2 never verify that the assertion was issued for that Source (no audience, Destination, or SubjectConfirmationData Recipient binding) and never record assertions already accepted, permitting replay. Attackers must therefore obtain an assertion minted for a different service provider or reuse a previously captured assertion; no authentik-side credentials or user interaction are required (PR:N/UI:N), which is why the issue scores 7.4 despite the High attack complexity driven by that prerequisite. Only SAML Sources are affected - SAML Providers and other Source types are explicitly not - and no public exploit code was identified at time of analysis, with no CISA KEV listing.
RemediationAI
Vendor-released patch: upgrade to 2026.2.7 (2026.2 branch), 2026.5.7 (2026.5 branch), or 2026.8.2 (2026.8 branch) - the 2026.8.0 and 2026.8.1 releases must move to 2026.8.2, and the upstream fixes land via pull requests 25957, 25962, 25967 and 25972 together with commits 287ea13cdc23c378abc20a7b71c9c7919a19a89a, 355d8cc3d755fbba05fc5fa90ffbcbe6469acddd, 54fac864a0b3bc00551af1908f662b3bf5cc6135 and 984b0162711f0d1988ed33544d0a671c93e4ec76; consult the advisory GHSA-cqj8-fxxf-9pg7 and the per-branch release notes before upgrading. If upgrading is not immediately possible, the highest-value compensating control is to disable the affected SAML Source (or all SAML Sources) in the authentik admin interface, which fully removes the attack surface at the cost of losing that SSO path for its users. Where the SAML Source must stay live, disable IdP-initiated SSO for it (the allow_idp_initiated setting) so that assertions lacking a matching InResponseTo are rejected, and ask the upstream IdP to emit strict audience restrictions limited to that authentik Source plus assertions with short NotOnOrAfter lifetimes, which shrinks but does not eliminate the replay window; note the patch's own 24-hour assertion-ID cache is the durable fix for replay and has no equivalent manual workaround. Additionally restrict network access to the SAML Source's ACS endpoint so that only the trusted IdP's addresses can POST to it, which blunts both cross-SP assertion reuse and replay from external positions but fails if the attacker can inject from the IdP's own network path. After patching, monitor authentik logs for 'Destination of Response does not match ACS URL', 'Replay attack detected' and MismatchedBinding/SuspiciousOperation events to detect prior or ongoing abuse attempts.
Affected VersionsENISA
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 1 package in euvd
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
The flaw is a CWE-287 improper-authentication defect in authentik's SAML 2.0 Source (service-provider side federation), in the response processor under authentik/sources/saml/processors/response.py. SAML Web Browser SSO responses carry a Response-level Destination attribute and, inside the signed assertion, a Subject element whose bearer SubjectConfirmation (Method urn:oasis:names:tc:SAML:2.0:cm:bearer) holds SubjectConfirmationData with Recipient, NotOnOrAfter, and InResponseTo. Correct SP behavior requires the response to be addressed to this SP's ACS URL and the assertion to carry an audience/recipient matching this SP and a request ID matching the login the SP initiated. The pre-fix code verified the XML signature and validity window but skipped Destination/Recipient comparison entirely, and its InResponseTo check only ran when the assertion's response-id cache was reachable; a prior partial mitigation cached only the Response ID for IdP-initiated flows rather than the assertion ID, so replayed assertions were accepted. The patch adds a MismatchedBinding exception plus _verify_destination, _verify_subject_confirmation (evaluating every bearer SubjectConfirmationData and accepting if one names this Source), and _verify_not_seen_before, which records a SHA-256 of the assertion ID in the cache key goauthentik.io/sources/saml/seen_assertion/<source_pk>/<hash> with a 24-hour timeout via cache.add. Affected software is identified by CPE cpe:2.3:a:goauthentik:authentik:*:*:*:*:*:*:*:*.
Know when Authentik gets its next vulnerability
- Watch products and get an email when something new is published
- Check this CVE against your own stack and servers
- Exploit and PoC references, threat intelligence from 22 sources
No credit card · 7-day full trial
Severity by source
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Unauthenticated network login bypass (PR:N) yielding full user impersonation (C:H/I:H), but AC:H because a valid signed assertion must first be obtained; no availability impact.
Primary rating from Vendor (GitHub_M).
CVSS VectorVendor: GitHub_M
Lifecycle Timeline
2DescriptionCVE.org
authentik is an open-source identity provider. Prior to 2026.2.7, 2026.5.7, and 2026.8.2, an authentik SAML Source verifies an assertion's signature and validity period but does not ensure that the identity provider issued the assertion for that Source or in response to a login request from that Source. The SAML Source also does not record already accepted assertions, allowing replay. An unauthenticated actor who possesses such a valid assertion can use an assertion intended for another service provider or reuse an earlier assertion to authenticate as the user named by the assertion. Only SAML Sources are affected; SAML Providers and other Source types are not affected. This issue is fixed in versions 2026.2.7, 2026.5.7, and 2026.8.2.
Technical POC Analysis
CWE-287 (Improper Authentication), with the advisory also mapping CWE-345 (Insufficient Verification of Data Authenticity).
Full technical POC analysis - root cause, step-by-step exploitation and patch breakdown - is part of the Pro and Business plans.
Executive ViewAI
authentik's SAML Source component contains an authentication bypass (CVE-2026-94612, CVSS 7.4) that allows anyone holding a valid, unexpired SAML assertion issued by a trusted identity provider to log in as the user named in that assertion - with no authentik credentials and no user interaction - because affected releases never verify the assertion was bound to that Source and never block reuse of previously accepted assertions. Any organization relying on authentik SAML Sources for workforce single sign-on should treat this as a potential full account-takeover path for named users, though exploitation requires an attacker to first obtain an assertion minted for a different service provider or replay a captured one. No public exploit code and no active exploitation have been identified, and vendor fixes are available.
Apply vendor patch.
Threat Intelligence Overview
NVD
CVE.org
EPSS
Vulnrichment
GitHub
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.
authentik is an open-source identity provider. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploi
authentik is an open-source Identity Provider focused on flexibility and versatility. Rated high severity (CVSS 8.8), th
authentik is an open-source Identity provider focused on flexibility and versatility. Rated medium severity (CVSS 6.4),
Authentication bypass in authentik identity provider (versions prior to 2025.12.6, 2026.2.4, and 2026.5.1) allows remote
authentik is an open-source Identity Provider. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploi
authentik is an open-source Identity Provider. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploi
authentik is an open-source identity provider. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploi
authentik is an open-source identity provider. After authorizing access to a RAC endpoint, authentik creates a token whi
Account takeover in authentik (goauthentik) identity provider before 2026.2.6 and 2026.5.5 allows an attacker holding an
Cross-site scripting in authentik identity provider versions prior to 2025.12.5 and 2026.2.3 allows remote attackers to
Code injection in authentik identity provider from 2021.3.1 through multiple versions. Users with delegated permissions
authentik is an open-source identity provider. Rated critical severity (CVSS 9.0), this vulnerability is remotely exploi
Exploit-DB