EUVD-2026-86122Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessIdentify internet-facing authentik SAML endpoint
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DeliveryCraft malformed SAML/XML message
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ExploitSend to /application/saml/* or /source/saml/*
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ExecutionTerminate worker handling request
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ImpactRepeat to sustain SAML traffic failures
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V2 - Validation and Business Logic Resource allocation limits
MITRE ATT&CK
1 technique across 1 tactic: Impact The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | Requires the authentik deployment to be configured with SAML in either the identity-provider role (serving /application/saml/*) or the SAML source role (serving /source/saml/*), with those endpoints reachable by the attacker; no authentication, credentials, or user interaction are needed (PR:N/UI:N). Limiting factors: only SAML endpoints are affected - deployments not using SAML, or using only OAuth/OIDC/LDAP/other protocols, are not exploitable; impact is partial and self-healing since workers auto-restart and database-backed sessions are not destroyed, so a single message causes only a brief failure and sustained degradation requires a continuous stream of malicious messages. |
| Impact | This is a genuine denial-of-service issue but not a top-tier emergency. The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H, base 7.5) correctly captures that an unauthenticated remote attacker can trigger it with low complexity and no user interaction against internet-facing SAML endpoints. However, the A:H rating slightly overstates real impact: the description makes clear this is a partial/degradation DoS - a malformed SAML message kills the worker handling /application/saml/* or /source/saml/*, the worker auto-restarts, database-backed sessions survive, and only SAML endpoints are affected (other protocols keep working). Sustained flooding is required to keep a 'share of legitimate traffic' failing, so it is closer to A:L partial availability loss than a full outage. There is no confidentiality or integrity impact. No EPSS score, no CISA KEV listing, and no public POC were provided, so exploitation is 'no public exploit identified at time of analysis' - this is not confirmed active exploitation. Priority should be driven by exposure: deployments using authentik as a SAML IdP or SAML source with those endpoints reachable from untrusted networks should patch promptly, but the lack of RCE/data impact and absence of exploitation signals place this below critical. |
| Exploit ScenarioDerived | An unauthenticated attacker locates an authentik instance exposed on the internet that serves SAML (as an identity provider or SAML source) and sends a malformed SAML message - for example one exploiting the XML parsing weakness fixed in the patch - to /application/saml/* or /source/saml/*. The message terminates the worker processing that request; by repeatedly sending such messages the attacker sustains a share of failed SAML authentication traffic. No public exploit code was identified, though the fix commits and added XML test cases reveal the affected parsing path. |
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Alert meAnalysisAIv1 – Sep 24, 2026
Malformed SAML messages sent to an authentik deployment that uses SAML either as an identity provider (/application/saml/*) or as a SAML source (/source/saml/*) can terminate the worker process handling the request, so every request assigned to that worker fails. No authentication or user interaction is required (CVSS:3.1/AV:N/AC:L/PR:N/UI:N), and because workers restart automatically and database-backed sessions survive, each message causes only a brief localised failure - sustained disruption requires a continuous stream of malicious messages, which is why the assessed availability impact is Low rather than High. Only SAML endpoints are affected; deployments using OAuth/OIDC/LDAP or other protocols are not exploitable, and no public exploit code was identified at time of analysis (CWE-770, CVSS 7.5 per the CVE record, adjusted to A:L in our independent assessment).
RemediationAI
Apply the vendor-released patches: upgrade to authentik 2026.2.7, 2026.5.7, or 2026.8.2 depending on your release train (tags version/2026.2.7, version/2026.5.7, version/2026.8.2; see GHSA-cxwx-9x59-28qm and the 2026.2/2026.5/2026.8 release notes). If an immediate upgrade is not possible, the most effective compensating control is to remove the exposure: if SAML is not actually used, disable the SAML provider/source applications so /application/saml/* and /source/saml/* return nothing - note that this breaks any SAML federation that is still in use. Where SAML must stay enabled, terminate it behind a reverse proxy or WAF that applies strict per-IP request rate limiting and payload-size caps on the SAML paths (for example nginx limit_req/limit_conn and client_max_body_size), accepting that aggressive limits can throttle legitimate IdP-initiated logins and SP traffic, and add blocking rules for requests whose body contains a DOCTYPE declaration, which the patched parser rejects outright; front authentik's SAML routes with a load balancer configured to retry failed requests on another worker to mask the transient failures caused by restarts. Monitor worker restarts and 5xx rates on the SAML endpoints as a detection signal, and note that upstream fix commits (03d19d63, 4cf2f803, 732adad2, a029f537) and PRs 25959/25964/25969/25974 are available if backporting is required.
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
authentik parses inbound SAML XML (AuthnRequest/Response messages) in a pool of worker processes using lxml, which wraps the libxml2/expat parsing stack. The root cause class is CWE-770 (Allocation of Resources Without Limits or Throttling): the parser accepted XML constructs such as DOCTYPE declarations, internal/external entity definitions, and maliciously deep element nesting without bounding their resource consumption, allowing a single small request to exhaust memory/CPU or otherwise raise an unhandled condition that kills the worker. The vendor fix introduces an authentik.lib.xml layer (UnsafeXML, lxml_from_string) that pre-scans the document prolog with Python's expat parser and rejects any DOCTYPE declaration - including UTF-16/UTF-32 encoded variants, internal subsets, and external system identifiers - before libxml2 ever sees it, refuses documents whose declared encoding does not match their content or cannot be validated, treats DOCTYPE-looking text inside comments or attribute values as harmless, and retains lxml's default nesting-depth limit. The affected CPE is cpe:2.3:a:goauthentik:authentik:*:*:*:*:*:*:*:*, i.e. all authentik builds predating the three fixed release branches, and the fix spans multiple SAML PRs (25959, 25964, 25969, 25974) plus commits 03d19d63, 4cf2f803, 732adad2 and a029f537.
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Unauthenticated network trigger with low complexity (AV:N/AC:L/PR:N/UI:N); availability lowered to A:L because workers auto-restart, sessions persist, and only SAML traffic partially degrades.
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 unauthenticated attacker can submit a malformed SAML message to an authentik deployment using SAML in either the identity-provider or SAML source role. The message can stop the worker handling /application/saml/* or /source/saml/*, causing the requests assigned to that worker to fail. Worker process termination and automatic restart do not destroy database-backed sessions, but continued malicious messages can cause a sustained share of legitimate traffic to fail. Other protocol implementations are not affected. This issue is fixed in versions 2026.2.7, 2026.5.7, and 2026.8.2.
Technical POC Analysis
Bug class: CWE-770 (Allocation of Resources Without Limits or Throttling), per the CVE metadata supplied with this request.
Full technical POC analysis - root cause, step-by-step exploitation and patch breakdown - is part of the Pro and Business plans.
Executive ViewAI
authentik, an open-source identity provider, is affected by a high-severity availability vulnerability in its SAML endpoints (CVE-2026-94613) that can cause brief worker process failures when malformed SAML messages are received. Organizations using authentik for SAML-based authentication-either as an identity provider or as a SAML source-may experience intermittent login disruptions, though the impact is localized and workers automatically restart. Leadership should prioritize patching because identity services are critical infrastructure, and a sustained attack could degrade authentication availability for dependent applications.
Apply vendor patch.
Threat Intelligence Overview
NVD
CVE.org
EPSS
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
Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.
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