THREATPORT/VULNERABILITY/CVE-2021-21276
CRITICAL SEVERITY

CVE-2021-21276

Polr vulnerability

CVSS
9.3
EPSS
7.2%
EPSS pct
94th
Exploited
No known
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.
Affected vendor
Polrproject
Affected product
Polr
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N
Weakness type (CWE)
  • CWE-863 — Incorrect Authorization
Published
2021-02-01

Risk analysis

Based on its CVSS vector, this vulnerability is exploitable over the network, low attack complexity, requiring no privileges, no user interaction. Successful exploitation leads to high impact to confidentiality, low impact to integrity.

Its EPSS score of 7.2% reflects a lower probability of exploitation activity in the wild over the next 30 days, placing it above 94% of all scored CVEs.

Check your external exposure to CVE-2021-21276

  • Confirm whether Polrproject Polr is running on any internet-facing host or subdomain.
  • Match discovered service fingerprints against the version affected by CVE-2021-21276.
  • Prioritise remediation if the asset is public, business-critical, or near authentication/payment flows.

How ThreatPort helps with CVE-2021-21276

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