How severe is CVE-2021-41303?

CVE-2021-41303 has a CVSS score of 9.8/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-41303?

CVE-2021-41303 affects the following packages: org.apache.shiro:shiro-core (Maven). Ecosystems affected: Maven.

How do I fix CVE-2021-41303?

Update org.apache.shiro:shiro-core to 1.8.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-41303 is resolved across your whole dependency graph.

How do I detect CVE-2021-41303 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.shiro:shiro-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-41303 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-2021-41303 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-41303 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2021-41303?

CVE-2021-41303 has an EPSS (Exploit Prediction Scoring System) score of 76.1%, 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-2021-41303?

CVE-2021-41303 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-2021-41303 published, and has it been updated?

CVE-2021-41303 was published on September 17, 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-2021-41303 — shiro-core

CRITICAL

CVE-2021-41303 is a critical-severity (CVSS 9.8) Improper Authentication vulnerability in org.apache.shiro:shiro-core. EPSS puts its 30-day exploitation probability at 76.1% (100th percentile). A fix is available for org.apache.shiro:shiro-core — see the affected versions and patch details below.

Apache Shiro vulnerable to a specially crafted HTTP request causing an authentication bypass

Also known asGHSA-f6jp-j6w3-w9hm

Published

Sep 17, 2021

Updated

Oct 24, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

76.1%probability of exploitation in next 30 days

Very High Risk-0.53%

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

1 pkg affected

☕org.apache.shiro:shiro-core

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 1.8.0, when using Apache Shiro with Spring Boot, a specially crafted HTTP request may cause an authentication bypass. Users should update to Apache Shiro 1.8.0.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.apache.shiro:shiro-core`	all versions	1.8.0`org.apache.shiro:shiro-core:1.8.0`

Affected Products

2 products · 3 configurations

Application

shiroapache

< 1.8.0

range

Application

financial services crime and compliance management studiooracle

2 versions

8.0.8.2.08.0.8.3.0

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-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.apache.shiro:shiro-core to 1.8.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-41303 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 1.8.0, when using Apache Shiro with Spring Boot, a specially crafted HTTP request may cause an authentication bypass. Users should update to Apache Shiro 1.8.0.

O3 Security · Impact-Aware SCA

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