VULNpocalypse

CVE-2021-21311: Adminer Server-Side Request Forgery Vulnerability

Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.

Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.

What it is

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.

Description quoted from the CVE record (assigned by GitHub_M, published 2021-02-11).

Weakness: CWE-918: Server-Side Request Forgery (SSRF)

How it can be exploited

Exploitable over the network with low attack complexity needing no privileges and no user interaction. Impact: 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

CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: yes. Technical impact: partial.

On CISA KEV since
2025-09-29
US federal deadline
2025-10-20
Ransomware use
Not known

Public exploit evidence (Exploit Observer)

Also known as: BDU:2021-02925, BDU:2026-01118, CNNVD-202102-1087, EUVD-2021-0576, GHSA-x5r2-hj5c-8jx6

VEDAS cluster: VEDAS:ANTEATERDINE

Exploit Observer links 8 pieces of public exploit code or detection modules that name this CVE or one of its aliases.

Exploit code and modules (8)

Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.

Vulnerability databases and vendor advisories (14)

Catalogue entries, not exploit evidence.

37 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.

VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.

Live scores

EPSS
0.985
very likely to be attacked soon
VEDAS
0.990
strong exploit evidence
On CISA KEV
Yes, since 2025-09-29
Detection rule
Nuclei · Suricata
EPSS (chance of attack)
10No cve-scores data 2026-02-22 to 2026-08-08no data0.1Added to CISA KEV 2025-09-29CVE-2021-21311 EPSS over time2025-042026-11-01
VEDAS (exploit evidence)
10No cve-scores data 2026-02-22 to 2026-08-08no data0.9Added to CISA KEV 2025-09-29CVE-2021-21311 VEDAS over time2025-042026-11-01

Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish. The vertical line is the day CISA added it to its exploited list.

VEDAS flagged this bug about 43 days before CISA confirmed attacks.

Who is affected

ProductAffectedNot affected
vrana adminerversion >= 4.0.0, < 4.7.9Not stated

Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.

Exploit Observer also maps it to: adminer adminer, packagist vrana/adminer, сообщество_свободного_программного_обеспечения adminer.

How to fix it

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.

Vendor guidance:

How to detect it

Nuclei template (active check)

Adminer - Server-Side Request Forgery

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.

Name and description quoted from the template, written by VEDAS.

The template sends 1 request (POST {{path}}); it decides using status, word matchers. Severity in the template: high. Marked as not yet verified against a live vulnerable target.

Run it against a host you own or are authorised to test:

bash
nuclei -u https://your-host -t CVE-2021-21311.yaml
Show the template (55 lines)
yaml
id: CVE-2021-21311

info:
  name: "Adminer - Server-Side Request Forgery"
  author: vedas-arpsyndicate
  severity: high
  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.
  reference:
    - https://www.exploit.observer/?keyword=CVE-2021-21311&match=exact
    - https://subdomain.center/?engine=ammonites&keyword=adminer&match=exact
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
    cvss-score: 7.2
    cve-id: CVE-2021-21311
    cwe-id: CWE-918
  metadata:
    verified: false
  tags: cve2021,cve,adminer,ssrf,vkev,kev,vuln
http:
  - raw:
      - |
        POST {{path}} HTTP/1.1
        Host: {{Hostname}}
        Content-Type: application/x-www-form-urlencoded

        auth[driver]=elastic&auth[server]=example.org&auth[username]={{to_lower(rand_base(8))}}&auth[password]={{to_lower(rand_base(8))}}&auth[db]={{to_lower(rand_base(8))}}

    payloads:
      path:
        - "/index.php"
        - "/adminer.php"
        - "/adminer/adminer.php"
        - "/adminer/index.php"
        - "/_adminer.php"
        - "/_adminer/index.php"

    attack: batteringram
    stop-at-first-match: true
    redirects: true
    max-redirects: 1

    matchers-condition: and
    matchers:
      - type: word
        part: body
        words:
          - "<title>400 - Bad Request</title>"
          - "&lt;title&gt;400 - Bad Request&lt;/title&gt;"
        condition: or

      - type: status
        status:
          - 403

CVE-2021-21311.yaml on GitHub

Suricata rules (network detection)

1 rule that alert on traffic matching this exploit: VEDAS CVE-2021-21311 Adminer - Server-Side Request Forgery. Add them to your Suricata rule set and reload.

Show the rules
suricata
alert http $EXTERNAL_NET any -> $HTTP_SERVERS $HTTP_PORTS (msg:"VEDAS CVE-2021-21311 Adminer - Server-Side Request Forgery"; flow:established,to_server; http.request_body; content:"auth[driver]=elastic&auth[server]=example.org&auth[username]"; nocase; fast_pattern; classtype:web-application-attack; reference:cve,CVE-2021-21311; reference:url,https://www.exploit.observer/?keyword=CVE-2021-21311&match=exact; reference:url,https://subdomain.center/?engine=ammonites&keyword=adminer&match=exact; sid:1011279; rev:1;)

CVE-2021-21311.rules on GitHub

References

Government sources

Other references

Other databases

Where this comes from

This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer, vedas-signatures. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.