CVE-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. A fix is available for github.com/crewjam/saml — see the affected versions and patch details below.
XML Processing error in github.com/crewjam/saml
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2020-27846 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 394,415 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
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
Impact
There are three vulnerabilities in the go encoding/xml package that can allow an attacker to forge part of a signed XML document. For details on this vulnerability see xml-roundtrip-validator
Patches
In version 0.4.3, all XML input is validated prior to being parsed.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/crewjam/saml | all versions | 0.4.3go get github.com/crewjam/saml@v0.4.3 |
Affected Products
fedorafedoraprojectgrafanagrafanaenterprise linuxredhatopenshift container platformredhatopenshift service meshredhatsamlsaml_projectResearch 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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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.
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…
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 8 | grafana-0:7.3.6-2.el8 | RHSA-2021:1859 |
| Red Hat OpenShift Container Platform 4.7 | openshift4/ose-grafana:v4.7.0-202102130115.p0 | RHSA-2020:5633 |
Frequently Asked Questions
Is CVE-2020-27846 in your dependencies?
Find it across Go, including transitive dependencies.