GHSA-4m6j-23p2-8c54 is a critical-severity (CVSS 9.1) Improper Authentication vulnerability in com.linecorp.armeria:armeria-saml. A fix is available for com.linecorp.armeria:armeria-saml — see the affected versions and patch details below.
Armeria SAML authentication bypass due to missing validation on unsigned SAML messages
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- 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-4m6j-23p2-8c54.
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-4m6j-23p2-8c54 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 377,166 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
com.linecorp.armeria:armeria-samlReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
Impact
The SAML implementation provided by armeria-saml currently accepts unsigned SAML messages (assertions, logout requests, etc.) as they are, rather than rejecting them by default. As a result, an attacker can forge a SAML message to authenticate themselves, despite the fact that such an unsigned SAML message should be rejected.
Patches
The vulnerability has been patched in Armeria version 1.27.2. All users who rely on armeria-saml older than version 1.27.2 must upgrade to 1.27.2 or later.
Workarounds
There is no known workaround for this vulnerability.
References
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | com.linecorp.armeria:armeria-saml | all versions | 1.27.2com.linecorp.armeria:armeria-saml:1.27.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for com.linecorp.armeria:armeria-saml, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update com.linecorp.armeria:armeria-saml to 1.27.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-4m6j-23p2-8c54 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-4m6j-23p2-8c54 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-4m6j-23p2-8c54. 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-4m6j-23p2-8c54 in your dependencies?
O3 Security finds GHSA-4m6j-23p2-8c54 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.