dbcve.org
Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 20 Oct 2025.
Debian LinuxOperating system · Debian

CVE-2021-21311

HIGH · 7.2 CVSS v3.1 Published 2021-02-11
Fix available
A fix is available. Upgrade to 4.7.9 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild High EPSS Public exploit Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

This is a server-side request forgery (SSRF) vulnerability in Adminer, an open-source database management tool written as a single PHP file. The vulnerability allows an attacker to induce the server to make crafted requests to arbitrary destinations, potentially accessing internal services or exfiltrating data. It affects Adminer versions 4.0.0 through 4.7.8, specifically versions bundling all database drivers.

MitigationUpgrade Adminer to version 4.7.9 or later. If immediate upgrading is not possible, restrict network access to Adminer interfaces and implement additional validation on any user-supplied URLs processed by the application.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Debian LinuxOperating system
Affected:= 9.0
AdminerApplication
Affected:>= 4.0.0, < 4.7.9

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Locate Adminer installation and identify version
    Find the Adminer PHP file (commonly named adminer.php, adminer-*.php, or inside a web directory) and open it in a text editor or run 'grep -i "version\|Adminer" <filename>' to find the version string, or check the file name if it contains a version number
    Affected if The installed version is 4.0.0 through 4.7.8 (not 4.7.9 or later)
  2. Confirm the exact version number
    Open the Adminer PHP file directly and search for a line containing the version number (often appears as a comment or defined constant near the top of the file)
    Affected if The version is less than 4.7.9
  3. Verify external database driver access is available
    Log into Adminer and check the login page or driver selection screen to see which database drivers are available/enabled (MySQL, PostgreSQL, SQLite, etc.)
    Affected if Any database driver is available and the server can connect to external network destinations
  4. Check if Adminer is exposed to untrusted networks
    Review firewall rules, network configuration, or web server access controls to determine if Adminer is accessible from outside the local network or from untrusted users
    Affected if Adminer is reachable from the internet or untrusted internal users without authentication barriers

You are affected if Adminer version 4.0.0 through 4.7.8 is installed and is accessible to users who could trigger the SSRF through database connection features.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 4.7.9 or later
Fixed in 4.7.9
Vendor patch github.com →
Interim mitigation

Upgrade Adminer to version 4.7.9 or later. If immediate upgrading is not possible, restrict network access to Adminer interfaces and implement additional validation on any user-supplied URLs processed by the application.

Recommended fix High confidence

Adminer 4.7.9 or later

  1. Identify the current Adminer version by checking the adminer.php file or the file header
  2. Download Adminer version 4.7.9 or later from the official source (e.g., https://www.adminer.org/)
  3. Replace the existing adminer.php file with the new version
  4. Ensure the new file has appropriate file permissions (e.g., readable by the web server)
  5. Verify the upgrade was successful by checking the Adminer version in the interface
  6. Test that database connections still work properly after the upgrade
Caveat None expected - this is a patch release addressing security vulnerability

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Debian Linux Exploited in the wild — priority engagement
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,060
Get it fixed fast

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,696.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2021-21311 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-21311 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data