CVE-2021-21276 Privilege escalation in Polr

2021-02-0100:00:00

CWE-863

GitHub_M

www.cve.org

polr

url shortener

privilege escalation

setup process

admin access

vulnerability

cookie headers

loose comparison

strict comparison

patch

version 2.3.0

security fix

CVSS3

9.3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

CHANGED

Confidentiality Impact

HIGH

Integrity Impact

LOW

Availability Impact

NONE

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N

AI Score

9.3

Confidence

High

EPSS

0.016

Percentile

87.4%

JSON

Polr is an open source URL shortener. in Polr before version 2.3.0, a vulnerability in the setup process allows attackers to gain admin access to site instances, even if they do not possess an existing account. This vulnerability exists regardless of users’ settings. If an attacker crafts a request with specific cookie headers to the /setup/finish endpoint, they may be able to obtain admin privileges on the instance. This is caused by a loose comparison (==) in SetupController that is susceptible to attack. The project has been patched to ensure that a strict comparison (===) is used to verify the setup key, and that /setup/finish verifies that no users table exists before performing any migrations or provisioning any new accounts. This is fixed in version 2.3.0. Users can patch this vulnerability without upgrading by adding abort(404) to the very first line of finishSetup in SetupController.php.

CNA Affected

[
  {
    "vendor": "cydrobolt",
    "product": "polr",
    "versions": [
      {
        "version": "< 2.3.0",
        "status": "affected"
      }
    ]
  }
]