CVE-2020-27846
CRITICALCVE-2020-27846 is a critical-severity (CVSS 9.8) CWE-115 vulnerability in github.com/crewjam/saml. 1 public exploit reference exists, so weaponization risk is real. O3 Security confirms whether CVE-2020-27846 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
XML Processing error in github.com/crewjam/saml
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
CVE-2020-27846 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 369,023 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
github.com/crewjam/samlReal-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
A signature verification vulnerability exists in crewjam/saml. This flaw allows an attacker to bypass SAML Authentication. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/crewjam/saml | all versions | 0.4.3 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/crewjam/saml. 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 github.com/crewjam/saml to 0.4.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-27846 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 CVE-2020-27846 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 CVE-2020-27846. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Grafana in the OpenShift Container Platform (OCP) and OpenShift ServiceMesh) uses oauth-proxy as an Auth Proxy, and therefore does not make use of the vulnerable SAML Authentication in the github.com/crewjam/saml module used by Grafana. Additionally, SAML is only available in the enterprise version of grafana, but as…
Frequently Asked Questions
Is CVE-2020-27846 in your dependencies?
O3 detects CVE-2020-27846 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.