---
id: "CVE-2021-21311"
kind: "vulnerability"
aliases: ["CVE-2021-21311"]
title: "Adminer is an open-source database management in a single PHP file"
severity: "high"
cvss: 7.2
epss: null
exploited: true
status: "open"
category: "other"
products: [{"name": "Adminer Adminer", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "adminer", "fixed": ["4.7.9"], "affected": ">= 4.0.0, < 4.7.9", "ecosystem": "vendor"}, {"name": "debian linux", "fixed": [], "affected": "= 9.0", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["adminer", "exploited", "other", "php", "self-hosted"]
not_affected_if: ["default-config"]
published_at: "2021-02-11T21:15:13+00:00"
first_seen_at: "2026-10-23T19:11:51+00:00"
updated_at: "2026-10-23T23:44:51+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-21311", "first_seen_at": "2026-10-23T19:11:51+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-21311", "first_seen_at": "2026-10-23T23:44:51+00:00"}]
---

# Adminer is an open-source database management in a single PHP file

Adminer, a PHP database administration tool, has a server-side request forgery flaw. A remote attacker can make the server send requests to internal addresses and read back potentially sensitive information.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Adminer Adminer affected ? fixed ?
- vendor:adminer affected >= 4.0.0, < 4.7.9 fixed 4.7.9
- vendor:debian linux affected = 9.0 fixed ?

## Fix

Upgrade Adminer to a fixed release per vendor instructions; the sources do not name the fixed version. Discontinue use if no mitigation is available, per CISA.

## Timeline

- 2026-10-23T19:11:51+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-21311
- 2026-10-23T23:44:51+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2021-21311

## From the sources

Adminer contains a server-side request forgery vulnerability that, when exploited, allows a remote attacker to obtain potentially sensitive information.

CISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_