Executive brief
Appsmith, a platform for building internal business tools and dashboards, is vulnerable to a security flaw that allows attackers to make the server send unauthorized requests. By exploiting this, an attacker could potentially access sensitive internal services, cloud metadata, or private network resources that are not intended to be public. This could lead to the exposure of internal data or unauthorized access to the organization's infrastructure.
Technical details
A Server-Side Request Forgery (SSRF) vulnerability exists in Appsmith's WebClientUtils component, specifically within the computeDisallowedHosts function. The application relies on a static string-based blacklist for host validation rather than performing CIDR-based range checks for private IP addresses (e.g., 10.0.0.0/8) or internal service names. A remote attacker can provide a URL pointing to internal infrastructure, Kubernetes API services, or cloud metadata endpoints (like Alibaba Cloud's 100.100.100.200) to bypass these checks. This allows for internal service enumeration, credential theft from metadata services, and potential privilege escalation. The issue is addressed in version 1.99.
Affected products
- Appsmith Appsmith <= 1.97
Timeline
- 2026-03-23: advisory: GitHub Security Advisory GHSA-9m89-5jw7-q5cr published
- 2026-04-02: disclosed: CVE-2026-5418 published to NVD
- 2026-04-02: patched: Version 1.99 released to address the vulnerability