Terrascan: Server-Side Request Forgery
CVE-2026-47358 is a high-severity server-side request forgery vulnerability in Terrascan from Tenable, with a CVSS 3.1 base score of 8.6 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected Terrascan versions: 1.18.3 and earlier. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.48% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of Terrascan you run against the affected versions below, and install the vendor's latest release.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- NoneNothing can be modified.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 9.2 | Critical | CNA (tenable.com) |
| CVSS 3.1 | 7.5 | High | CNA (tenable.com) |
| CVSS 3.1 | 8.6 | High | NVD |
Official description
Terrascan v1.18.3 and prior are vulnerable to Server-Side Request Forgery (SSRF) via external URL resolution in uploaded IaC templates when running in server mode. When Terrascan parses uploaded ARM templates or CloudFormation templates, it resolves external URLs referenced within those templates via hashicorp/go-getter with all default detectors enabled, including FileDetector. An unauthenticated remote attacker can upload an ARM template containing a templateLink.uri or parametersLink.uri field, or a CloudFormation template containing an AWS::CloudFormation::Stack TemplateURL field, pointing to an attacker-controlled URL. Terrascan will fetch the attacker-controlled URL server-side. Unlike SSRF via the remote scan endpoint, file:// URLs are directly usable without requiring an X-Terraform-Get redirect, enabling local file read. This affects deployments running terrascan in server mode (terrascan server), which binds to 0.0.0.0 with no authentication. Note: Terrascan was archived in August 2023 and no patch will be released.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Server-Side Request Forgery
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.
How developers prevent this class of flaw
- If there is a known list of applications, IP, hostname, and/or domains to which the product is allowed to communicate, then use allowlists to ensure that outgoing requests are restricted to these known entities. The allowlists could be in the application code or possibly enforced by firewalls or network segmentation.
- If the product is expected to be able to connect to arbitrary IP addresses or domains, consider using a denylist that includes private network addresses, internal domain names, etc. The denylist could be in the application code or possibly enforced by firewalls or network segmentation.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Other references
- github.com/tenable/terrascanProduct
Other vulnerabilities in Terrascan
- 8.6 High severity
- 8.6 High severity
Recent Server-Side Request Forgery vulnerabilities
- 7.5 High severity
- 7.3 High severity
- 7.4 High severity
- 7.3 High severity
- 7.3 High severity
- 7.7 High severity
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