grav-plugin-api: Permissive Cross-domain Security Policy with Untrusted Domains
CVE-2026-63407 is a high-severity permissive cross-domain security policy with untrusted domains vulnerability in grav-plugin-api from Grav, with a CVSS 3.1 base score of 8.2 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. Affected grav-plugin-api versions: < 1.0.0-rc.16. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.38% 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 grav-plugin-api you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Grav | grav-plugin-api | < 1.0.0-rc.16 | Not stated |
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
- RequiredA user must take an action such as opening a file or link.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- LowLimited modification of data is possible.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N. Scored by CNA (github.com).
Official description
Grav API Plugin is a RESTful API for Grav CMS that provides full headless access to your site's content. Prior to 1.0.0-rc.16, the Grav API plugin CorsMiddleware returns Access-Control-Allow-Origin: * and permissive OPTIONS responses for authenticated /api/v1 endpoints. JavaScript from any origin can submit an attacker-obtained JWT through the Authorization or X-API-Token header, read the authenticated response, and perform write operations with the token owner's privileges, enabling data exfiltration and account modification. This issue is fixed in version 1.0.0-rc.16.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Permissive Cross-domain Security Policy with Untrusted Domains
The product uses a web-client protection mechanism such as a Content Security Policy (CSP) or cross-domain policy file, but the policy includes untrusted domains with which the web client is allowed to communicate.
How developers prevent this class of flaw
- Define a restrictive Content Security Policy or cross-domain policy file.
- Avoid using wildcards in the CSP / cross-domain policy file. Any domain matching the wildcard expression will be implicitly trusted, and can perform two-way interaction with the target server.
- For Flash, modify crossdomain.xml to use meta-policy options such as 'master-only' or 'none' to reduce the possibility of an attacker planting extraneous cross-domain policy files on a server.
More Permissive Cross-domain Security Policy with Untrusted Domains vulnerabilities (CWE-942)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other vulnerabilities in grav-plugin-api
- 9.8 Critical severity
- 7.2 High severity
- 8.7 High severity
- 8.7 High severity
- 8.7 High severity
- 8.7 High severity
Recent Permissive Cross-domain Security Policy with Untrusted Domains vulnerabilities
- 9.3 Critical severity
- 7.4 High severity
- 9.8 Critical severity
- 7.1 High severity
- 9.3 Critical severity
- 7.2 High severity
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