How severe is CVE-2021-21311?

CVE-2021-21311 has a CVSS score of 7.2/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-21311?

CVE-2021-21311 affects the following packages: vrana/adminer (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2021-21311?

Update vrana/adminer to version 4.7.9 or later. Run your dependency manager's update command and verify no transitive dependencies pin the vulnerable version. Use O3 Security's SCA scanner to confirm the fix is applied across your entire dependency tree.

Is CVE-2021-21311 actively exploited in the wild?

Yes. There are 3 known exploit references for CVE-2021-21311, including 2 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2021-21311?

CVE-2021-21311 has an EPSS (Exploit Prediction Scoring System) score of 94.1%, placing it in the 100th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

Is CVE-2021-21311 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2021-21311 (Adminer Server-Side Request Forgery Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2025-09-29. CISA required all US federal civilian agencies to remediate this vulnerability by 2025-10-20. The required action was: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

Is there exploit tooling available for CVE-2021-21311?

A Nuclei detection template exists for CVE-2021-21311, meaning automated scanners can fingerprint it. Public exploit tooling significantly increases real-world risk — prioritize patching and ensure detection coverage. Exploit tooling should only ever be used in isolated, authorized testing environments.

When was CVE-2021-21311 published, and has it been updated?

CVE-2021-21311 was published on February 11, 2021 and was last updated on April 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CISA KEV·Added 2025-09-29 — agencies required to remediate by 2025-10-20

🐘 Packagist

CVE-2021-21311

HIGH

SSRF in adminer

Also known asGHSA-x5r2-hj5c-8jx6

Published

Feb 11, 2021

Updated

Apr 10, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

3 known

EPSS Exploitation Probability

via FIRST.org ↗

94.1%probability of exploitation in next 30 days

Very High Risk100th percentile+0.02%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

1 pkg affected

🐘vrana/adminer

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

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.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`vrana/adminer`	all versions	4.7.9

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Adminer is an open-source database management in a single PHP file. In a…

github.comNVDJun 2021

Adminer is an open-source database management in a single PHP file. In a…

github.comGithubFeb 2022

Frequently Asked Questions

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.

O3 Security · Impact-Aware SCA

Is CVE-2021-21311 in your stack?

O3 detects CVE-2021-21311 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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