Raw vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:NSummary
CVE-2026-21433 is a high-severity SSRF (CWE-918) vulnerability in Emlog Emlog. Its CVSS base score is 7.7 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 20th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to AC-4 (Information Flow Enforcement) and SI-10 (Information Input Validation) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-21433 is a server-side Out-of-Band (OOB) request and Server-Side Request Forgery (SSRF) vulnerability in Emlog, an open source website building system. Versions up to and including 2.5.19 are affected, specifically through the handling of uploaded SVG files via the /admin/media.php endpoint. An attacker can upload a crafted SVG containing external resource references, and when the server processes or renders the file—such as during thumbnailing, previewing, or sanitization—it issues an HTTP request to the attacker's controlled host. The vulnerability is rated 7.7 on the CVSS 3.1 scale (AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N) and maps to CWE-918 (Server-Side Request Forgery).
Exploitation requires low privileges (PR:L), typically an authenticated user with upload capabilities, allowing network-accessible (AV:N) attacks with low complexity (AC:L) and no user interaction (UI:N). Successful exploitation enables server-side SSRF/OOB interactions, permitting the attacker to probe internal networks and potentially expose metadata or credentials from the server's perspective. The changed scope (S:C) amplifies the confidentiality impact (C:H) by leveraging the server's higher privileges to access resources otherwise unreachable.
The primary advisory, published on GitHub at https://github.com/emlog/emlog/security/advisories/GHSA-6rwr-c8hc-mjj4, confirms the issue and notes that as of the publication date (2026-01-02), no patched versions of Emlog are available, leaving affected installations without official mitigations.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-0754
Vulnerability Data
Emlog is an open source website building system. Versions up to and including 2.5.19 are vulnerable to server-side Out-of-Band (OOB) requests / SSRF via uploaded SVG files. An attacker can upload a crafted SVG to http[:]//emblog/admin/media[.]php which contains external resource…
more
references. When the server processes/renders the SVG (thumbnailing, preview, or sanitization), it issues an HTTP request to the attacker-controlled host. Impact: server-side SSRF/OOB leading to internal network probing and potential metadata/credential exposure. As of time of publication, no known patched versions are available.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V1.3.6V1.5.3V5.3.2V10.4.7
Mitigating Controls (NIST 800-53 r5) AI
Information flow enforcement can restrict which destinations the server is allowed to contact on behalf of users.
Input validation directly stops untrusted URLs from being accepted and fetched without destination checks.
Boundary protection limits the network reach of server-initiated requests even if SSRF occurs.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure development practices directly include input validation and destination allow-listing that prevent SSRF.
Runtime monitoring of web applications and services can detect anomalous outbound requests indicative of SSRF.
Vulnerability identification processes can discover and record SSRF flaws in web applications.
Network segmentation and egress controls can limit the damage from successful SSRF requests.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Operational threat data describing SSRF campaigns can be used to tighten outbound-request allow-lists and detection rules before attackers exploit them.