GHSA-c3m2-jqmq-pvp3 is a high-severity (CVSS 8.5) Improper Input Validation vulnerability in goauthentik.io. O3 Security confirms whether GHSA-c3m2-jqmq-pvp3 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
authentik's XML Signature Wrapping in SAML Source ACS allows authentication as arbitrary federated user
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-c3m2-jqmq-pvp3.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-c3m2-jqmq-pvp3 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 0 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
goauthentik.ioReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Summary
authentik's SAML Source ACS endpoint is vulnerable to XML Signature Wrapping when validating upstream SAML responses. An attacker with any account at the upstream IdP can reuse a valid signed assertion to authenticate as another federated user.
Patches
authentik 2026.5.1, 2026.2.4 and 2025.12.6 fix this issue.
Impact
Affected: authentik deployments using a SAML Source for upstream SAML federation with signed assertions, or signed responses without signed assertions. Not affected: deployments that do not use SAML Source for upstream SAML federation.
The SAML Source trusts that the verified XML signature belongs to the assertion or response that authentik later consumes. A crafted SAML response can make signature verification succeed against the attacker's original signed assertion while authentik reads identity data from a different forged assertion.
An attacker first completes a legitimate login to the upstream IdP and captures the signed SAML response sent through their browser. They then submit a modified response to the ACS endpoint where the valid signature still verifies, but the consumed assertion contains a victim identifier or attacker-chosen attributes.
The attacker can authenticate as a victim who has previously used the SAML Source, or as a local user matched by forged email or username when those matching modes are enabled.
Workarounds
Disable affected SAML Sources, or block access to their ACS endpoints.
For more information
If there are any questions or comments about this advisory:
- Send an email to [email protected]
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | goauthentik.io | all versions | 0.0.0-20260528144335-a370d76d23c7 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for goauthentik.io. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update goauthentik.io to 0.0.0-20260528144335-a370d76d23c7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-c3m2-jqmq-pvp3 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-c3m2-jqmq-pvp3 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-c3m2-jqmq-pvp3. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-c3m2-jqmq-pvp3 in your dependencies?
O3 detects GHSA-c3m2-jqmq-pvp3 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.