CVE-2021-41303Network attack vector

Unauthenticated access via crafted HTTP requests

Published Sep 17, 2021 · Updated Aug 4, 2024

Authentication bypass in Apache Shiro before 1.8.0 allows remote attackers to reach protected Spring Boot resources via crafted HTTP requests. Apache has not published the crafted request form or the request-processing mismatch that causes Shiro's authentication filter to be bypassed. The issue is limited to applications that integrate Shiro with Spring Boot; successful requests receive whatever protected access the host application exposes.

CVSS severity9.8
Critical
EPSS probability76.66%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Apache Shiro before 1.8.0 allows remote attackers to reach protected Spring Boot resources via crafted HTTP requests. Apache has not published the crafted request form or the request-processing mismatch that causes Shiro's authentication filter to be bypassed. The issue is limited to applications that integrate Shiro with Spring Boot; successful requests receive whatever protected access the host application exposes.

The record

CVE
CVE-2021-41303
Published
Sep 17, 2021
Updated
Aug 4, 2024
Vendor
The Apache Software Foundation
Product
Apache Shiro
Classifications
CWE-287, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 17, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Apache Shiro <1.8.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Shiroversion=Apache Shiro <1.8.0

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-287Improper Authentication
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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