CVE-2021-21311: Adminer Server-Side Request Forgery Vulnerability
- Is it exploited?
Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 29 Sep 2025, 1,691 days after the CVE record was published.
- How likely is exploitation in the next 30 days?
- 98.5%
EPSS score, percentile 99.9 of all scored records
- How severe?
- 7.2 High
CVSS v3.1 base score, given by the CNA
- What should I do?
Required action (CISA), due 20 Oct 2025: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
The CVE record links no vendor advisory, patch or mitigation.
- Which versions are affected?
Affected: >= 4.0.0, < 4.7.9
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
What to do
Required action, set by CISA
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
CISA due date for this action: 20 October 2025.
Advisories and patches
The CVE record links no vendor advisory, patch or mitigation.
Linked from CISA's catalog entry
- https://github.com/vrana/adminer/security/advisories/GHSA-x5r2-hj5c-8jx6
- https://nvd.nist.gov/vuln/detail/CVE-2021-21311
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | >= 4.0.0, < 4.7.9 |
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
About this vulnerability
Adminer contains a server-side request forgery vulnerability that, when exploited, allows a remote attacker to obtain potentially sensitive information.
Summary: CISA's KEV catalog, as of 28 Oct 2026.
- CISA added CVE-2021-21311 to its Known Exploited Vulnerabilities (KEV) catalog on 29 Sep 2025.
- CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
- The due date CISA sets for the required action is 20 Oct 2025.
- The CVE record was published on 11 Feb 2021, 1,691 days before it was added to KEV.
- The CVE record carries a CVSS v3.1 base score of 7.2 (High), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 98.5% (percentile 99.9), as of 28 Oct 2026.
- CISA's SSVC assessment in the CVE record: exploitation active, automatable yes, technical impact partial.
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.
Description
SSRF in 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.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
Weakness
- CWE-918: Server-Side Request Forgery (SSRF)
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.
Timeline
| Date | Event |
|---|---|
| 11 Feb 2021 | CVE record published |
| 29 Sep 2025 | Added to CISA KEV |
| 20 Oct 2025 | CISA due date for the required action |
| 21 Oct 2025 | CVE record last updated |