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.
do firstApply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Can a WAF block it? Partly. SSRF makes the server call a URL the attacker picks. A WAF can block well-known targets such as cloud metadata addresses, but not every internal host.
Also consider: egress filter · IMDSv2
Based on the weakness type only; no CVE-specific evidence yet. We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.
Is CVE-2021-21311 being exploited?
Yes. CVE-2021-21311 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.
How severe is CVE-2021-21311?
CVE-2021-21311 is rated High with a CVSS score of 7.2. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2021-21311?
Yes. A fix has been recorded for CVE-2021-21311. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2021-21311 affect?
CVE-2021-21311 affects adminer:adminer, debian:debian_linux. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
- affected>= 4.0.0 and < 4.7.9
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.
public exploits
Unvetted proof-of-concept code on GitHub: 3 GitHub proofs of concept · 1 Nuclei template
- Adminer <4.7.9 - Server-Side Request Forgery · detection template · high
- llhala/CVE-2021-21311 · 8 ★
- omoknooni/CVE-2021-21311 · 3 ★
- Sudo-WP/sudowp-adminer · 1 ★
Listed so you can judge urgency, not as a recommendation to run anything. GitHub “proofs of concept” are unvetted: some are fake or carry malware. Exploit-DB marks the entries its staff verified.
cisa ssvc
- exploitation
- active
- automatable
- yes
- technical impact
- partial
Assessed by CISA 27 Sept 2025 (SSVC 2.0.3).
timeline
- 11 Feb 2021Published
- 14 Feb 2022First proof-of-concept repository on GitHub (unvetted) · 367 days (about 1 year) later
- 27 Sept 2025CISA SSVC assessment: exploitation active · 1,321 days (about 4 years) later
- 29 Sept 2025Added to CISA KEV (exploited in the wild) · 2 days later
- 20 Oct 2025CISA remediation due date (US federal agencies) · 21 days later
- 21 Oct 2025CVE record last updated · 2 days later
- 2 Nov 2026Analysed by vulneraibility.com · 377 days (about 1 year) later
also known as
- Linkgithub.com /vrana/adminer/security/advisories/GHSA-x5r2-hj5c-8jx6
- Linkgithub.com /vrana/adminer/files/5957311/Adminer.SSRF.pdf
- Linkpackagist.org /packages/vrana/adminer
- Linkgithub.com /vrana/adminer/commit/ccd2374b0b12bd547417bf0dacdf153826c83351
- Linklists.debian.org /debian-lts-announce/2021/03/msg00002.html
- Linkcisa.gov /known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-21311
sources
- CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
- NVD: CVSS and CPE data
- CISA KEV catalog: exploitation, date added, due date
- CISA Vulnrichment (ADP): SSVC decision points
- FIRST EPSS: exploit probability and percentile
- Nuclei templates: detection templates
- PoC-in-GitHub: GitHub repositories that claim a proof of concept
- OSV: advisory aliases and downstream package versions
- Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.