CVE-2026-55455

Appsmith: SSRF in REST API / GraphQL datasource plugins via insufficient host denylist

State: Published
Severity: 5.3 Medium
Published: Jun 24, 2026
Updated: Jun 25, 2026
Reserved: Jun 16, 2026

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.

Scores

CVSS	Score	Vector	Source
4.0	5.3 Medium	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N	GitHub_M

Weaknesses

CWE-918 Server-Side Request Forgery (SSRF)

Affected Products

Product	Versions
appsmithappsmithorg	< 2.1Affected

References

https://github.com/appsmithorg/appsmith/security/advisories/GHSA-m23h-pvf3-2m7p

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