CVE-2020-17523 — shiro-web
CRITICALCVE-2020-17523 is a critical-severity (CVSS 9.8) Improper Authentication vulnerability in org.apache.shiro:shiro-web. 2 public exploit references exist, so weaponization risk is real. A fix is available for org.apache.shiro:shiro-web — see the affected versions and patch details below.
Authentication bypass in Apache Shiro
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-2020-17523 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE sits: patch-first territory.
Where this sits among everything scored
Of 377,238 CVEs with a current EPSS score, this one falls in the 50–90% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
org.apache.shiro:shiro-web☕org.apache.shiro:shiro-spring☕org.apache.shiro:shiro-spring-boot-starterReal-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
Apache Shiro before 1.7.1, when using Apache Shiro with Spring, a specially crafted HTTP request may cause an authentication bypass.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.apache.shiro:shiro-web | all versions | 1.7.1org.apache.shiro:shiro-web:1.7.1 |
| ☕Maven | org.apache.shiro:shiro-spring | all versions | 1.7.1org.apache.shiro:shiro-spring:1.7.1 |
| ☕Maven | org.apache.shiro:shiro-spring-boot-starter | all versions | 1.7.1org.apache.shiro:shiro-spring-boot-starter:1.7.1 |
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 org.apache.shiro:shiro-web, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.apache.shiro:shiro-web to 1.7.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-17523 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 CVE-2020-17523 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2020-17523. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2020-17523 in your dependencies?
O3 Security finds CVE-2020-17523 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.