How severe is CVE-2020-17523?

CVE-2020-17523 has a CVSS score of 9.8/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2020-17523?

CVE-2020-17523 affects the following packages: org.apache.shiro:shiro-web (Maven), org.apache.shiro:shiro-spring (Maven), org.apache.shiro:shiro-spring-boot-starter (Maven). Ecosystems affected: Maven.

How do I fix CVE-2020-17523?

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.

How do I detect CVE-2020-17523 in my Maven dependencies?

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.

How do I mitigate CVE-2020-17523 if there is no patch (or I can't update yet)?

Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Is CVE-2020-17523 actively exploited in the wild?

Yes. There are 2 known exploit references for CVE-2020-17523, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2020-17523?

CVE-2020-17523 has an EPSS (Exploit Prediction Scoring System) score of 85.9%, placing it in the 100th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

What type of vulnerability is CVE-2020-17523?

CVE-2020-17523 is classified as Improper Authentication (CWE-287). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2020-17523 published, and has it been updated?

CVE-2020-17523 was published on February 3, 2021 and was last updated on October 24, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕

☕ Maven

Not in CISA KEV

CRITICAL severity

CVE-2020-17523 — shiro-web

CRITICALFix: apache/shiro#263

CVE-2020-17523 is a critical-severity (CVSS 9.8) Improper Authentication vulnerability in org.apache.shiro:shiro-web. 2 public exploit or proof-of-concept references are indexed, 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

Also known asGHSA-v98j-7crc-wvrj

Published

Feb 3, 2021

Updated

Oct 24, 2026

Affected

3 pkgs

Patched

3 / 3

Exploits

2 known

Exploitation data as of Nov 3, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

85.9%probability of exploitation in next 30 days

Very High Risk0.00%

Lower risk than most CVEs100th percentile — riskier than 100% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

3 pkgs affected

☕org.apache.shiro:shiro-web☕org.apache.shiro:shiro-spring☕org.apache.shiro:shiro-spring-boot-starter

Real-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

3 total 3 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.apache.shiro:shiro-web`	all versions	1.7.1`org.apache.shiro:shiro-web:1.7.1`
☕Maven	`org.apache.shiro:shiro-spring`	all versions	1.7.1`org.apache.shiro:shiro-spring:1.7.1`
☕Maven	`org.apache.shiro:shiro-spring-boot-starter`	all versions	1.7.1`org.apache.shiro:shiro-spring-boot-starter:1.7.1`

Affected Products

1 product · 1 configurations

Application

shiroapache

< 1.7.1

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Apache Shiro before 1.7.1, when using Apache Shiro with Spring, a specia…

github.comGithubFeb 2021

Detection & mitigation playbook

Open-source dependency

Detect
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
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

Apache Shiro before 1.7.1, when using Apache Shiro with Spring, a specially crafted HTTP request may cause an authentication bypass.

O3 Security · Impact-Aware SCA

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