Cyber Threat Intelligence
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HIGH · CVSS 7.2 CISA Known Exploited Vulnerability

CVE-2021-21311

Adminer Server-Side Request Forgery Vulnerability

Adminer Adminer

Adminer is an open-source database management in a single PHP file. In adminer from version 4.0.0 and before 4.7.9 there is a server-side request forgery vulnerability. Users of Adminer versions bundling all drivers (e.g. `adminer.php`) are affected. This is fixed in version 4.7.9.

CVSS
7.2
HIGH
EPSS
98.5%
30-day exploitation
Ransomware groups
0
recorded exploiting
Published
11 Feb 2021
CWE-918

Exploitation status

CISA Known Exploited Vulnerabilities

Listed by CISA on 29 September 2025. US federal agencies were required to remediate it by 20 October 2025.

EPSS — exploitation probability

FIRST puts the probability of exploitation activity in the next 30 days at 98.5%, which is higher than 99.9% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.

CVSS vector

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

Frequently asked questions

Is CVE-2021-21311 being exploited by ransomware groups?

No ransomware group in this database is currently recorded as exploiting CVE-2021-21311.

What does CVE-2021-21311 affect?

CVE-2021-21311 affects Adminer Adminer. Adminer is an open-source database management in a single PHP file. In adminer from version 4.0.0 and before 4.7.9 there is a server-side request forgery vulnerability. Users of Adminer versions bundling all drivers (e.g. `adminer.php`) are affected. This is fixed in version 4.7.9.

How severe is CVE-2021-21311?

CVE-2021-21311 is rated HIGH with a CVSS base score of 7.2. EPSS puts the probability of exploitation in the next 30 days at 98.5%, higher than 99.9% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 20 October 2025.

How should organisations respond to CVE-2021-21311?

Apply the vendor patch for Adminer Adminer as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.