What is CVE-2021-21311?

CVE-2021-21311 is a high-severity vulnerability in Adminer, classified under Server-Side Request Forgery (SSRF). CVSS score: 7.2/10. Published 2021-02-11.

How severe is CVE-2021-21311?

High severity. CVSS v3 base score is 7.2 out of 10.

Is CVE-2021-21311 known to be exploited?

Yes. CVE-2021-21311 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-09-29), indicating it is being actively exploited. 40 public proof-of-concept repositories are indexed.

SSRF in Adminer

CVE-2021-21311

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.

Vulnerability class: SSRF (Server-Side Request Forgery)

Published 2021-02-11 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.2 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.985 (99.9th percentile), scored 2026-10-17.

Very high probability of exploitation in the next 30 days — among the top 0.1% most-likely-to-be-exploited CVEs. 100th percentile — 99.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.905 · newest: 0.985 · change: +0.080

Affected products

Adminer
Vrana Adminer — versions >= 4.0.0, < 4.7.9
Debian Linux — versions 9.0

Weakness classification (CWE)

CWE-918 — Server-Side Request Forgery (SSRF)

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2025-09-29. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2025-10-20.

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.

Public proof-of-concept exploits

References

github.com/vrana/adminer/security/advisories/GHSA-x5r2-hj5c-8jx6 (Patch, Third Party Advisory)
github.com/vrana/adminer/files/5957311/Adminer.SSRF.pdf (Exploit, Third Party Advisory)
packagist.org/packages/vrana/adminer (Product, Third Party Advisory)
github.com/vrana/adminer/commit/ccd2374b0b12bd547417bf0dacdf153826c83351 (Patch)
lists.debian.org/debian-lts-announce/2021/03/msg00002.html (mailing-list, Mailing List, Third Party Advisory)
134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource)

Frequently asked questions

What is CVE-2021-21311?: CVE-2021-21311 is a high-severity vulnerability in Adminer, classified under Server-Side Request Forgery (SSRF). CVSS score: 7.2/10. Published 2021-02-11.
How severe is CVE-2021-21311?: High severity. CVSS v3 base score is 7.2 out of 10.
Is CVE-2021-21311 known to be exploited?: Yes. CVE-2021-21311 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-09-29), indicating it is being actively exploited. 40 public proof-of-concept repositories are indexed.