# CVE-2026-5418: Appsmith SSRF in WebClientUtils via improper host validation

Source: https://junglewise.ai/threats/cve-2026-5418-appsmith-ssrf-in-webclientutils-via-improper-host-validation  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-02. Updated: 2026-07-24  
License: CC BY 4.0 with a link back

CVE-2026-5418 · Severity: high · CVSS 7.3 · Published 2026-04-02

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.

Technologies: [Appsmith](https://junglewise.ai/threats/technologies/appsmith). Vendors: [Appsmith](https://junglewise.ai/threats/vendors/appsmith).

## Quick answers

**Is CVE-2026-5418 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-5418 being exploited in the wild.

**How severe is CVE-2026-5418?** High severity, with a CVSS score of 7.3, published 2 April 2026.

**Which products and versions are affected?** Appsmith <= 1.97.

**Is there a fix for CVE-2026-5418?** A patch was published on 2026-04-02: Version 1.99 released to address the vulnerability Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-5418 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-5418?** Check whether you run Appsmith at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## 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

## References

- [https://github.com/appsmithorg/appsmith/](https://github.com/appsmithorg/appsmith/)
- [https://github.com/appsmithorg/appsmith/security/advisories/GHSA-9m89-5jw7-q5cr](https://github.com/appsmithorg/appsmith/security/advisories/GHSA-9m89-5jw7-q5cr)
- [https://vuldb.com/submit/780190](https://vuldb.com/submit/780190)
- [https://vuldb.com/vuln/354855](https://vuldb.com/vuln/354855)
- [https://vuldb.com/vuln/354855/cti](https://vuldb.com/vuln/354855/cti)

## Related threats

- [Appsmith OS command execution via supervisord XML-RPC interface](https://junglewise.ai/threats/cve-2026-50189-appsmith-os-command-execution-via-supervisord-xml-rpc-interface)
- [Appsmith stored XSS in SQL query editor autocomplete](https://junglewise.ai/threats/cve-2026-7299-appsmith-stored-xss-in-sql-query-editor-autocomplete)
- [Appsmith missing authentication in instance management API endpoints](https://junglewise.ai/threats/cve-2026-34411-appsmith-missing-authentication-in-instance-management-api)