CVE-2021-21276Public exploitNetwork attack vector

Unauthenticated administrator takeover via setup-key type juggling

Published Feb 1, 2021 · Updated Aug 3, 2024

Incorrect authorization in Cydrobolt Polr before 2.3.0 allows remote attackers to create an administrator account via /setup/finish. SetupController::finishSetup loosely compares the cookie-supplied setup_auth_key with TMP_SETUP_AUTH_KEY, so Boolean true matches the nonempty secret through PHP type juggling. The endpoint remains usable after initial setup because no users-table guard exists, letting an unauthenticated attacker provision a new administrator and control links and settings.

CVSS severity9.3
Critical
EPSS probability7.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect authorization in Cydrobolt Polr before 2.3.0 allows remote attackers to create an administrator account via /setup/finish. SetupController::finishSetup loosely compares the cookie-supplied setup_auth_key with TMP_SETUP_AUTH_KEY, so Boolean true matches the nonempty secret through PHP type juggling. The endpoint remains usable after initial setup because no users-table guard exists, letting an unauthenticated attacker provision a new administrator and control links and settings.

The record

CVE
CVE-2021-21276
Published
Feb 1, 2021
Updated
Aug 3, 2024
Vendor
Cydrobolt
Product
Polr
Classifications
CWE-863, T1136, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 1, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=< 2.3.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Cydrobolt · Polrversion=< 2.3.0

Published CVSS scores

9.3GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N
6.4NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:N

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-863Incorrect Authorization
T1136Create Account
T1190Exploit Public-Facing Application

Public exploit references

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Technologies

Your stack

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Your stack

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