CVE-2020-17523Public exploitNetwork attack vector

Unauthenticated access via trimmed request-path tokens

Published Feb 3, 2021 · Updated Aug 4, 2024

Authentication bypass in Apache Shiro before 1.7.1 allows remote attackers to access protected Spring resources via crafted HTTP requests. The AntPathMatcher path-tokenization logic trims whitespace from request-path segments, so Shiro can miss a protected pattern while Spring still routes the resource. Exploitation requires a Shiro-secured Spring application with a matching protected route; successful requests reach that resource without authentication.

CVSS severity9.8
Critical
EPSS probability85.91%
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 1.7.1 allows remote attackers to access protected Spring resources via crafted HTTP requests. The AntPathMatcher path-tokenization logic trims whitespace from request-path segments, so Shiro can miss a protected pattern while Spring still routes the resource. Exploitation requires a Shiro-secured Spring application with a matching protected route; successful requests reach that resource without authentication.

The record

CVE
CVE-2020-17523
Published
Feb 3, 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. Feb 3, 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=before 1.7.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Shiroversion=before 1.7.1

Published CVSS scores

9.0NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:C
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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.

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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 exploitPublished

Weakness, pattern, technique

CWE-287Improper Authentication
T1190Exploit Public-Facing Application

Public exploit references

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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