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Medium

Craft CMS has a host header injection leading to SSRF via resource-js endpoint

  • Disclosed: 14.04.2026
  • Updated: 11.10.2026 10:22

Summary

The resource-js endpoint in Craft CMS allows unauthenticated requests to proxy remote JavaScript resources. When trustedHosts is not explicitly restricted (default configuration), the application trusts the client-supplied Host header.

This allows an attacker to control the derived baseUrl, which is used in prefix validation inside actionResourceJs(). By supplying a malicious Host header, the attacker can make the server issue arbitrary HTTP requests, leading to Server-Side Request Forgery (SSRF).

Details

The vulnerability exists in AppController::actionResourceJs().

The function validates that the url parameter starts with assetManager->baseUrl. However, baseUrl is derived from the current request host. If trustedHosts is not configured, the Host header is fully attacker-controlled.

Attack chain:

  1. Attacker sends request with controlled Host header.
  2. Application derives baseUrl from the malicious Host.
  3. url parameter is required to start with this baseUrl.
  4. Validation passes.
  5. Guzzle performs a server-side HTTP request to the attacker-controlled host.
  6. SSRF occurs.

This does not rely on string parsing bypass. It relies on Host header trust.

PoC (safe reproduction steps)

Environment:

  • Craft CMS 5.9.12
  • Default configuration (no trustedHosts restriction)
  • Docker deployment

  1. Start a listener inside the container: python3 -m http.server 9999

  2. Send a request to resource-js with a controlled Host header.

  3. Observe that the internal listener receives a request (OOB confirmation).

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
Composer package craftcms/cms >= 5.0.0-RC1, < 5.9.15, >= 4.0.0-RC1, < 4.17.9 5.9.15, 4.17.9

References

CVSS score -
CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:P
Weakness (CWE)
CWE-918
Platform
Composer
Package
craftcms/cms
Disclosed
14.04.2026
Updated
11.10.2026 10:22

Sources and licenses

OSV / GitHub Advisory Database - GHSA-95wr-3f2v-v2wh - 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.

All (127) in the archive
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

Severity:
  1. Craft CMS: Passkey login accepts replayed WebAuthn assertions
    Critical CVE-2026-72780 >= 5.0.0-RC1, < 5.10.5 5.10.5
  2. Craft CMS: Arbitrary user password reset leading to administrator account takeover
    High CVE-2026-72786 >= 5.0.0-RC1, < 5.10.8 5.10.8
  3. Craft CMS: Authenticated RCE through Twig sandbox escape
    High CVE-2026-72781 >= 5.0.0-RC1, < 5.10.7, >= 4.0.0-RC1, < 4.18.3 5.10.7, 4.18.3
  4. Craft CMS: Authenticated RCE via `condition.config` JSON cleanse bypass
    High CVE-2026-72778 >= 5.0.0-RC1, < 5.10.6, >= 4.0.0-RC1, < 4.18.2 5.10.6, 4.18.2
  5. Craft CMS: RCE via missing cleanseConfig in FieldsController::actionRenderCardPreview
    High CVE-2026-56382 >= 5.5.0, < 5.9.14 5.9.14
  6. Craft CMS: Potential authenticated Remote Code Execution via referrer redirect
    High CVE-2026-55794 >= 5.9.0, < 5.10.0 5.10.0
  7. Craft CMS: DOM XSS via GitHub issue title in CraftSupport widget
    High CVE-2026-55790 >= 5.0.0-RC1, < 5.9.23, >= 4.0.0-RC1, < 4.17.16 5.9.23, 4.17.16
  8. Craft CMS Vulnerable to Unauthorized Deletion of Destination Folders During Forced Moves
    High CVE-2026-50282 >= 5.0.0-RC1, < 5.9.21, >= 4.0.0-RC1, < 4.17.14 5.9.21, 4.17.14
  9. Craft CMS's mass assignment via id in newAttributes during bulk duplicate overwrites existing elements
    High CVE-2026-50281 >= 5.7.0, < 5.9.21 5.9.21
  10. Craft CMS: Missing peer-permission check in `AssetsController::actionDeleteFolder` allows deletion of other users' assets
    High CVE-2026-50284 >= 5.0.0-RC1, < 5.9.22, >= 4.0.0-RC1, < 4.17.15 5.9.22, 4.17.15
  11. Craft CMS: Authorship spoofing in `entries/save-entry` via pre-check/post-mutation authorization gap
    High CVE-2026-50279 >= 5.0.0-RC1, < 5.9.21 5.9.21
  12. Craft CMS: Blind SSRF and Arbitrary JavaScript Injection via Host Header Poisoning in actionResourceJs
    Critical CVE-2026-55791 >= 5.0.0-RC1, < 5.10, >= 4.0.0-RC1, < 4.18 5.10, 4.18
  13. Craft CMS's Missing Volume Permission Check in AssetsController::actionShowInFolder Allows Information Disclosure
    High CVE-2026-44012 >= 5.0.0-RC1, < 5.9.18 5.9.18
  14. Craft CMS has Potential Authenticated Remote Code Execution via Malicious Attached Behavior
    High CVE-2026-44011 >= 4.0.0, < 4.17.12, >= 5.0.0, < 5.9.18 4.17.12, 5.9.18
  15. Craft CMS's Missing Authorization in GraphQL Address Resolver Allows Cross-Scope PII Disclosure
    High CVE-2026-44010 >= 5.0.0, < 5.9.18, >= 4.0.0, < 4.17.12 5.9.18, 4.17.12
  16. Craft CMS has a host header injection leading to SSRF via resource-js endpoint this entry
    Medium CVE-2026-41130 >= 5.0.0-RC1, < 5.9.15, >= 4.0.0-RC1, < 4.17.9 5.9.15, 4.17.9
  17. Craft CMS is Vulnerable to Authenticated Remote Code Execution via Malicious Attached Behavior
    High CVE-2026-33157 >= 5.6.0, < 5.9.13 5.9.13
  18. Craft CMS Vulnerable to Privilege Escalation/Bypass through UsersController->actionImpersonateWithToken()
    High CVE-2026-32267 >= 4.0.0-RC1, < 4.17.6, >= 5.0.0-RC1, < 5.9.12 4.17.6, 5.9.12
  19. Craft CMS vulnerable to behavior injection RCE ElementIndexesController and FieldsController
    High CVE-2026-32264 >= 4.0.0-RC1, < 4.17.5, >= 5.0.0-RC1, < 5.9.11 4.17.5, 5.9.11
  20. Craft CMS vulnerable to behavior injection RCE via EntryTypesController
    High CVE-2026-32263 >= 5.6.0, < 5.9.11 5.9.11
  21. CraftCMS has an RCE vulnerability via relational conditionals in the control panel
    High CVE-2026-31857 >= 5.0.0-RC1, < 5.9.9, >= 4.0.0-beta.1, < 4.17.4 5.9.9, 4.17.4
  22. CraftCMS's `ElementSearchController` Affected by Blind SQL Injection
    High CVE-2026-31858 >= 5.0.0-RC1, < 5.9.9 5.9.9
  23. Craft CMS has unauthenticated activation email trigger with potential user enumeration
    High CVE-2026-29069 >= 5.0.0-RC1, < 5.9.0-beta.2, >= 4.0.0-RC1, < 4.17.0-beta.2 5.9.0-beta.2, 4.17.0-beta.2
  24. Craft CMS Vulnerable to Authenticated RCE via "craft.app.fs.write()" in Twig Templates
    Critical CVE-2026-28697 >= 5.0.0-RC1, < 5.9.0-beta.1, >= 4.0.0-RC1, < 4.17.0-beta.1 5.9.0-beta.1, 4.17.0-beta.1
  25. Craft CMS has IDOR via GraphQL @parseRefs
    High CVE-2026-28696 >= 4.0.0-RC1, < 4.17.0-beta.1, >= 5.0.0-RC1, < 5.9.0-beta.1 4.17.0-beta.1, 5.9.0-beta.1
  26. Craft CMS has Cloud Metadata SSRF Protection Bypass via DNS Rebinding
    High CVE-2026-27127 >= 5.0.0-RC1, < 5.8.23, >= 3.5.0, < 4.16.19 5.8.23, 4.16.19
  27. Craft CMS Vulnerable to potential authenticated Remote Code Execution via malicious attached Behavior
    High CVE-2026-25498 >= 5.0.0-RC1, < 5.8.22, >= 4.0.0-RC1, < 4.16.18 5.8.22, 4.16.18
  28. Craft CMS: GraphQL Asset Mutation Privilege Escalation
    High CVE-2026-25497 >= 5.0.0-RC1, < 5.9.0-beta.1, >= 4.0.0-RC1, < 4.17.0-beta.1 5.9.0-beta.1, 4.17.0-beta.1
  29. Craft CMS Vulnerable to SQL Injection in Element Indexes via `criteria[orderBy]`
    High CVE-2026-25495 >= 5.0.0-RC1, < 5.8.22, >= 4.0.0-RC1, < 4.16.18 5.8.22, 4.16.18
  30. Craft CMS vulnerable to potential authenticated Remote Code Execution via malicious attached Behavior
    High CVE-2025-68455 >= 5.0.0-RC1, < 5.8.21, >= 4.0.0-RC1, < 4.16.17 5.8.21, 4.16.17
  31. Unauthenticated Craft CMS users can trigger a database backup
    High CVE-2025-68456 >= 5.0.0-RC1, < 5.8.21, >= 3.0.0, < 4.16.17 5.8.21, 4.16.17
  32. Craft CMS Contains a Potential Remote Code Execution Vulnerability via Twig SSTI
    High CVE-2025-46731 >= 4.0.0-RC1, < 4.14.13, >= 5.0.0-RC1, < 5.6.15 4.14.13, 5.6.15
  33. Craft CMS Allows Remote Code Execution
    Critical · 10.0 Exploited in attacks CVE-2025-32432 >= 3.0.0-RC1, < 3.9.15, >= 4.0.0-RC1, < 4.14.15, >= 5.0.0-RC1, < 5.6.17 3.9.15, 4.14.15, 5.6.17
  34. Craft CMS has a potential RCE with a compromised security key
    High · 8.0 Exploited in attacks CVE-2025-23209 >= 5.0.0-RC1, < 5.5.8, >= 4.0.0-RC1, < 4.13.8 5.5.8, 4.13.8
  35. Craft CMS has potential RCE when PHP `register_argc_argv` config setting is enabled
    Critical · 9.8 Exploited in attacks CVE-2024-56145 >= 5.0.0-RC1, < 5.5.2, >= 4.0.0-RC1, < 4.13.2, >= 3.0.0, < 3.9.14 5.5.2, 4.13.2, 3.9.14
  36. Craft CMS vulnerable to Potential Remote Code Execution via missing path normalization & Twig SSTI
    High · 7.2 CVE-2024-52293 >= 4.0.0-RC1, < 4.12.2, >= 5.0.0-RC1, < 5.4.3 4.12.2, 5.4.3
  37. Craft CMS Arbitrary System File Read
    High · 7.7 CVE-2024-52292 >= 5.0.0-alpha.1, < 5.4.9, >= 3.5.13, < 4.12.8 5.4.9, 4.12.8
  38. Local File System Validation Bypass Leading to File Overwrite, Sensitive File Access, and Potential Code Execution
    High · 8.4 CVE-2024-52291 >= 5.0.0-RC1, < 5.4.6, >= 4.0.0-RC1, < 4.12.5 5.4.6, 4.12.5
  39. Craft CMS SQL injection vulnerability via the GraphQL API endpoint
    Critical · 9.8 CVE-2024-37843 <= 3.7.31 no fix
  40. Craft CMS Feed-Me
    High · 7.5 CVE-2023-36260 < 4.6.2 4.6.2
Show more (11) Showing 40 of 51

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