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CWE-73Weakness · CWE-73

CVE-2026-61873

HIGH · 8.1 CVSS v3.1 Published 2026-07-15
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
87/100
Remediation priority · High
Remotely reachable Zero-click 6 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Grav before 9.1.8 contains an arbitrary file write vulnerability in the Form plugin's process.save.filename parameter, which is validated against path traversal before Twig processing but never re-validated after rendering. Attackers can submit form data containing path traversal sequences that are processed through Twig templates, allowing them to write arbitrary files including PHP webshells to the web root or other sensitive directories.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Grav's Form plugin validates the process.save.filename parameter against path traversal BEFORE Twig template processing, but fails to re-validate the rendered filename AFTER Twig processing completes. This allows attackers to submit form data with path traversal sequences (e.g., ../../webshell.php) that pass initial validation but are processed through Twig templates to write arbitrary files including PHP webshells to the web root or sensitive directories.

MitigationUpgrade to Grav version 9.1.8 or later, which implements re-validation of the filename parameter after Twig rendering. Until patched, disable the Form plugin or implement additional input validation at the web server level.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Grav CMS core version
    Check the version file at /system/defines.php or look for 'VERSION' in /system/src/Grav/Common/Grav.php. Alternatively, check composer.json in the root for the 'grav' package version.
    Affected if The installed Grav version is earlier than 9.1.8 and the Form plugin is in use.
  2. Identify Form plugin version and status
    Examine the plugin directory at /user/plugins/form/ and locate the manifest file (blueprints.yaml) or composer.json within that folder to determine the plugin version. Check if the plugin folder exists and is enabled in /user/config/system.yaml under plugins section.
    Affected if The Form plugin version is earlier than 9.1.8 or the plugin is installed and enabled.
  3. Locate form configurations using process.save.filename
    Search YAML form configuration files in /user/pages/ and /user/config/ for the 'process.save.filename' parameter. Use grep or manually inspect form YAML files (*.yaml) in the pages and config directories.
    Affected if Forms are configured with process.save.filename parameter, which enables the vulnerable code path.
  4. Verify Twig template processing is enabled for forms
    Check the form YAML configurations to confirm that Twig processing is enabled (typically via 'twig: true' in the form or process section). Also verify the form includes save processing.
    Affected if Twig template processing is enabled for forms that use process.save.filename, allowing the second-stage bypass.
  5. Check web root file permissions
    Inspect file permissions on the web root directory (document root). Verify if the web server user has write access to the web root and sensitive directories.
    Affected if The web server process has write permissions to the web root, which would allow an attacker to successfully write a webshell if exploited.

You are affected if you are running Grav CMS with the Form plugin enabled (version earlier than 9.1.8), have forms configured with process.save.filename, and have Twig processing enabled for those forms.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to Grav version 9.1.8 or later, which implements re-validation of the filename parameter after Twig rendering. Until patched, disable the Form plugin or implement additional input validation at the web server level.

Recommended fix Moderate confidence

Grav 9.1.8 or later

  1. 1. Backup your Grav installation, including all files, the vendor directory, and the user/data directories.
  2. 2. If using Composer, run `composer update` to fetch the latest Grav core packages.
  3. 3. Alternatively, download Grav 9.1.8 or later from the official GitHub releases at github.com/getgrav/grav.
  4. 4. Replace the existing Grav core files with the new version, preserving your user/ directory and configuration.
  5. 5. Clear the cache directory (cache/twig/, cache/doctrine/, etc.) to ensure the patched code is used.
  6. 6. Verify the Form plugin is updated to the latest version compatible with Grav 9.1.8.
  7. 7. Test that forms still function correctly, especially any custom form configurations.

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing6.0 h
  • Review / QA4.0 h
20.0 hours of engineering $3,500
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-61873 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data