CVE-2026-55455: CWE-918: Server-Side Request Forgery (SSRF) in appsmithorg appsmith
Appsmith is a platform to build admin panels, internal tools, and dashboards. Prior to 2.1, the outbound HTTP host filter applied by WebClientUtils (used by the REST API and GraphQL datasource plugins) validates hosts against an exact-match string denylist. The comprehensive address-class check (loopback, any-local, link-local, fc00::/7) exists only on a separate code path used by SMTP, not by the HTTP plugin path. As a result, an authenticated user can craft outbound requests that reach loopback-bound services inside the container. This vulnerability is fixed in 2.1.
AI Analysis
Technical Summary
Appsmith before version 2.1 uses WebClientUtils for outbound HTTP requests in REST API and GraphQL datasource plugins. The host validation applies an exact-match denylist but lacks a comprehensive address-class check for loopback and local addresses, unlike the SMTP code path. This allows authenticated users to craft SSRF attacks targeting internal loopback services within the container. The vulnerability is resolved in version 2.1 by improving host validation.
Potential Impact
An authenticated user can exploit this SSRF vulnerability to send outbound HTTP requests to internal loopback services within the container, potentially accessing internal resources not intended to be exposed externally. The impact is limited by the requirement for authentication and the medium CVSS score reflects moderate risk.
Mitigation Recommendations
Upgrade Appsmith to version 2.1 or later, where this SSRF vulnerability is fixed by enhanced host validation. No other official remediation or temporary fixes are documented. Patch status is not explicitly confirmed in the advisory, but the fix is stated to be in version 2.1.
CVE-2026-55455: CWE-918: Server-Side Request Forgery (SSRF) in appsmithorg appsmith
Description
Appsmith is a platform to build admin panels, internal tools, and dashboards. Prior to 2.1, the outbound HTTP host filter applied by WebClientUtils (used by the REST API and GraphQL datasource plugins) validates hosts against an exact-match string denylist. The comprehensive address-class check (loopback, any-local, link-local, fc00::/7) exists only on a separate code path used by SMTP, not by the HTTP plugin path. As a result, an authenticated user can craft outbound requests that reach loopback-bound services inside the container. This vulnerability is fixed in 2.1.
CVSS v4.0
Score 5.3medium
Affected software
pkg:github/appsmithorg/appsmithRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Appsmith before version 2.1 uses WebClientUtils for outbound HTTP requests in REST API and GraphQL datasource plugins. The host validation applies an exact-match denylist but lacks a comprehensive address-class check for loopback and local addresses, unlike the SMTP code path. This allows authenticated users to craft SSRF attacks targeting internal loopback services within the container. The vulnerability is resolved in version 2.1 by improving host validation.
Potential Impact
An authenticated user can exploit this SSRF vulnerability to send outbound HTTP requests to internal loopback services within the container, potentially accessing internal resources not intended to be exposed externally. The impact is limited by the requirement for authentication and the medium CVSS score reflects moderate risk.
Mitigation Recommendations
Upgrade Appsmith to version 2.1 or later, where this SSRF vulnerability is fixed by enhanced host validation. No other official remediation or temporary fixes are documented. Patch status is not explicitly confirmed in the advisory, but the fix is stated to be in version 2.1.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-06-16T22:10:37.607Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a3c501e4853345fc1e45c5a
Added to database: 06/24/2026, 21:46:06 UTC
Last enriched: 07/01/2026, 22:45:06 UTC
Last updated: 08/08/2026, 12:41:11 UTC
Views: 82
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