CVE Alert: CVE-2021-21311 – vrana – 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.
AI Summary Analysis
Risk verdict
Urgent: exploitation is reported as active for this SSRF flaw in affected Adminer versions, with network access and no user interaction required.
Why this matters
An attacker can trigger SSRF to reach internal services from a publicly reachable Adminer instance, risking data exposure and potential secondary access to internal systems. Even low- to moderate-severity impact on confidentiality and integrity can facilitate probing of internal networks or access to database endpoints.
Most likely attack path
Vector: network; no authentication required and no user interaction. The scope isChanged, so successful SSRF could affect resources beyond the initial access. An automated exploit is indicated, enabling rapid, repeated attempts to reach internal endpoints from exposed Adminer deployments.
Who is most exposed
Public-facing Adminer deployments or deployments bundled with all drivers (adminer.php) and placed in shared hosting or exposed web server environments are most at risk; these are common in small to mid-scale web apps and CMS integrations.
Detection ideas
- Unusual outbound HTTP requests from the web server targeting private IP ranges or internal services.
- Logs showing SSRF-like patterns (requests to internal hosts or non-web destinations originated from PHP processes).
- Spike in outbound calls from the Adminer host without corresponding user activity.
- Adminer version detected as < 4.7.9 in inventory or scans.
- Anomalous access attempting to fetch remote resources from within a single PHP file deployment.
Mitigation and prioritisation
- Upgrade to 4.7.9 or later immediately; verify all instances and patch promptly.
- Restrict Adminer access to trusted networks; require strong authentication or IP allowlisting.
- Implement outbound network controls and WAF/IPS rules to block SSRF patterns targeting internal endpoints.
- Enhance logging and alerting for SSRF indicators; run regular inventory to confirm patch status.
- Consider removing or relocating public Adminer deployments if feasible; document patch window and change-management notes.
- If KEV is true or EPSS ≥ 0.5 (verification needed), escalate to priority 1.
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