Grav vulnerabilities

Grav prior to 3.8.5 in the Login plugin twofa_cancel task accepts a client-controlled _redirect field without a nonce and allows an unauthenticated request to set an external http, https, or protocol-relative Location target. Controller::execute() applies the field when taskTwofa_cancel() sets no redirect, and Grav::getRedirectResponse() accepts the target through Uri::isExternal(), enabling phishing redirects from a trusted Grav host.

Grav before 2.0.14 contains a stored cross-site scripting vulnerability in the Security::detectXss() function (system/src/Grav/Common/Security.php). All XSS detection patterns use the PCRE /u (UTF-8) modifier, so a single invalid UTF-8 byte anywhere in page content causes preg_match() to return false for every pattern, silently bypassing the save-time XSS safety gate (Validation::checkSafety()). An authenticated attacker with page-edit permissions (without the security.xss_whitelist privilege) can store malicious JavaScript that executes in the browser of a visitor who views the affected page.

Grav before 2.0.15 contains a stored cross-site scripting vulnerability in the audio and video media rendering through the sourceParsedownElement method. The media URL fragment is concatenated unescaped into rawHtml source elements, allowing attackers to inject arbitrary HTML and JavaScript that executes in viewers' sessions.

Grav before version 2.0.15 contains a stored cross-site scripting vulnerability in the detectXss() function where unpaired quotes in unquoted attribute values bypass event-handler detection. Authenticated editors can inject event handlers like onerror= that pass validation and execute in visitor browsers when page content is rendered.

Grav before 2.0.15 contains a path traversal vulnerability in the static asset server within index.php that uses string prefix matching instead of directory-boundary validation. Unauthenticated attackers can access files in sibling directories by exploiting directory names that extend the base path string, such as requesting assets-secret when assets is the configured base.

Grav versions from 1.5.2 through 2.0.12 contain a stored cross-site scripting vulnerability in the Security::detectXss() function (system/src/Grav/Common/Security.php). The event-handler scan is anchored at `<` and uses `[^>]*?`, which cannot cross the first literal `>`; when a `>` appears inside a quoted attribute value the browser keeps the tag open and parses a subsequent event handler (e.g. onerror), so the detector and browser disagree. A page editor without admin.super privileges can save page content such as `<img src=x title=">" onerror=alert(document.domain)>`, which is accepted, stored, and executed in the site origin when any visitor (including unauthenticated users) views the page. Fixed in 2.0.13.

Grav before version 2.0.1 contains a decompression bomb vulnerability in the ZipArchiver::extract() method, which lacks limits on uncompressed size, file count, and nesting depth. Attackers can supply a crafted ZIP archive that expands to fill available disk space, causing denial of service by exhausting storage resources.

Grav before version 2.0.2 contains a Twig sandbox bypass that allows a page author (any admin.pages user, or anyone able to write to user/pages) to exfiltrate configuration secrets. Although the sandbox replaces the 'config' variable with a redacted facade and strips Config::get/toArray from the method allowlist, the raw container remains accessible via the allow-listed grav.offsetGet('config'), which returns the real Config object. Allow-listed object-dumping filters (json_encode, print_r, yaml_encode) then serialize that object at the PHP level without invoking the sandbox method gate, exposing the full config tree including plugin secrets such as SMTP credentials, API keys, and plugin DB credentials.

Grav before version 2.0.0 (up to 2.0.0-rc.9 and the 2.0 branch) contains a stored CSS injection vulnerability in the Markdown image resize() media action. Prior media hardening rejects direct ?style= payloads and unsafe attribute() fallbacks, but the resize() action in Excerpts::processMediaActions() writes caller-controlled values directly into the image's styleAttributes. A lower-privileged content editor who can edit page Markdown can store a crafted image URL with semicolon-delimited CSS declarations in the resize parameters, which are rendered into the final <img style=...> attribute when a higher-privileged reviewer/admin views the page or preview.

Grav before version 2.0.0-beta.2 contains an XML external entity injection (XXE) vulnerability in SVG file upload processing that allows authenticated attackers to read arbitrary files. The application uses simplexml_load_string without disabling external entity loading, enabling attackers to inject XXE payloads via malicious SVG files.

Grav is a file-based web platform. Prior to version 2.0.0-rc.2, the Twig sandbox allow-list permitted any user with the admin.pages role to call config.toArray() within a page body, dumping the entire merged site configuration, including all plugin secrets.

Grav is a file-based web platform. Prior to version 2.0.0-beta.2, a low-privileged user could inject an svg element, leading to an XSS attack that could escalate to dumping system information available under /admin/config/info when a Super Admin visits the page.

Grav before 2.0.14 fails to guard the access field in the core group blueprint with the required security@: admin.super restriction. A delegated admin.users operator can save a group with access[admin][super]=true to escalate to super-admin, gaining scheduler and Twig evaluation capabilities.

Grav 2.0.4 (fixed in 2.0.7) contains a remote code execution vulnerability in Blueprint::dynamicData(). The function passes a Class::method callable string and its arguments directly to call_user_func_array() without any allowlist. Because the form plugin routes page frontmatter through this path, an authenticated account with admin.pages (or api.pages.write) permission can plant a malicious callable directive in a page. The command executes as the web-server user whenever anyone – including an unauthenticated visitor – accesses the page.

In grav before 1.7.49.5, a SSRF (Server-Side Request Forgery) vector may be triggered via Twig templates when page content is processed by Twig and the configuration allows undefined PHP functions to be registered.

Grav is a file-based Web platform. Prior to 1.8.0-beta.27, due to improper authorization checks when modifying critical fields on a POST request to /admin/pages/{page_name}, an editor with only permissions to change basic content on the form is now able to change the functioning of the form through modifying the content of the data[_json][header][form] which is the YAML frontmatter which includes the process section which dictates what happens after a user submits the form which include some important actions that could lead to further vulnerabilities. This vulnerability is fixed in 1.8.0-beta.27.

Grav before 2.0.16 contains an incomplete default denylist in the Twig sandbox configuration that fails to block access to system configuration secrets. Attackers with page-edit permission can use config.get() or config.toArray() in Twig templates to retrieve sensitive values like system.cache.redis.password when config_access is enabled.

Grav before 2.0.16 allows sandboxed Twig templates to access sensitive User fields through allow-listed offsetGet() and offsetexists() methods that lack field filtering. Attackers with page-edit permissions can call offsetGet() on User objects to extract hashed passwords and 2FA secrets, enabling offline password cracking and authentication bypass.

Grav before 2.0.16 contains a path traversal vulnerability in MediaUploadTrait::deleteFile() that allows authenticated users with media management permissions to delete arbitrary files by supplying filenames with directory traversal sequences. The method validates only the basename portion of the filename while preserving unvalidated directory paths containing ../ sequences that are passed to unlink(), enabling deletion of files outside the intended media storage directory.

Grav before 3.9.2 fails to validate untrusted Host headers in the sendInvitationEmail() function when constructing token-bearing invitation links. Attackers can manipulate the Host header to poison invitation links and redirect users to attacker-controlled domains, bypassing the require_trusted_host protection which only covers password reset flows.

Grav prior to 2.0.7 has a vulnerability in Blueprint::dynamicData() in system/src/Grav/Common/Data/Blueprint.php that sends an editor-controlled Class::method provider and arguments to call_user_func_array() without rejecting dangerous callback parameters. An account with admin.pages or api.pages.write can use Grav\Common\Utils::arrayFilterRecursive() as a trampoline with system as the callback, place a command in page frontmatter, and execute that command as the web server user when the page is viewed. This issue is fixed in version 2.0.7.

Grav before version 2.0.4 contains .htaccess security rules that compare directory and file-extension patterns case-sensitively, without the [NC] flag. On case-insensitive filesystems, an unauthenticated attacker can use uppercase variants to bypass the rules and retrieve files under user/accounts or user/config, including password hashes and security configuration. This issue is fixed in version 2.0.4.

Grav prior to 2.0.4 allowlists the regex_replace filter and function, and GravExtension::regexReplace() passes an editor-controlled pattern directly to preg_replace(). When security.twig_content.process_enabled is enabled, an authenticated page editor can publish a catastrophically backtracking pattern that consumes PHP worker CPU and denies service to site visitors.

Grav prior to 2.0.2 permits grav.offsetGet('config') to return the raw configuration object and allows json_encode, print_r, yaml_encode, and string filters to serialize that object without passing through GravSecurityPolicy::checkMethodAllowed. A user with page-author permissions can render sandboxed content that exposes plugins.* configuration secrets, including SMTP credentials, API keys, and plugin database credentials.

Grav prior to 2.0.1 in ZipArchiver::extract() passes archives to ZipArchive::extractTo() without enforcing the system.gpm.archive uncompressed-size, file-count, or nesting-depth limits. Code using Archiver::create('zip') to extract an attacker-controlled archive can exhaust disk space or inodes and make the site unavailable.

Grav before version 2.0.15 contains an arbitrary file write vulnerability in the Blueprint dynamic-data bare-function validation that uses an incomplete denylist instead of a positive allowlist. Attackers with page-edit or blueprint-config access can invoke the error_log function through a data directive to append PHP payloads to web-accessible files, achieving remote code execution.

Grav versions before 2.0.13 fail to properly validate backup profile root paths, allowing attackers to archive directories outside GRAV_ROOT when not in the hard-coded deny-list. Attackers with profile editor access can configure backup profiles with traversal paths to expose sensitive files from locations like /opt, /mnt, or /srv.

Remote code execution (RCE) vulnerability in Grav versions 1.7.0 through 2.0.9. FlexDirectory::dynamicDataField() calls call_user_func_array() on attacker-controlled input without restricting dangerous functions like exec or system. An authenticated user with create or update permissions on any Flex directory can execute arbitrary shell commands on the server.

Grav is vulnerable to stored XSS in shortcode attributes because the XSS scan only matches literal angle brackets. An attacker with admin.pages permission can inject malicious JavaScript that executes in any viewer's browser, including administrators.

Grav before version 2.0.4 contains a regular expression denial of service (ReDoS) vulnerability in the regex_replace filter and function, which are allowlisted in the Twig content sandbox. When Twig processing in page content is enabled (disabled by default), an authenticated page editor can supply a catastrophically backtracking PCRE pattern that is passed directly to PHP's preg_replace(), causing unbounded CPU consumption and denial of service to the web server process.

Vulnerability in Grav before version 2.0.4: unrestricted cURL protocols in webhooks. Authenticated users with api.webhooks.write permission can create webhooks with file://, dict://, or gopher:// URLs.

Grav before version 2.0.4 contains a two-factor authentication bypass vulnerability in the login plugin where the regenerate2FASecret task checks only user existence, not authorization, during the pending TOTP challenge window. Attackers who know the victim's password can call this task without a CSRF nonce to overwrite the 2FA secret with an attacker-chosen value, compute a valid TOTP code, and complete authentication while reducing 2FA to password-only protection.

Grav before version 2.0.4 ships a default .htaccess file whose rules blocking access to sensitive file types (.yaml, .php, .json, etc.) lack the [NC] flag, making extension matching case-sensitive. On case-insensitive filesystems (Windows/NTFS, macOS/HFS+, or Docker volume mounts), an unauthenticated attacker can request these files with uppercase or mixed-case extensions (e.g., .YAML, .PHP) to bypass the restrictions and read sensitive configuration files that may contain API keys and credentials.

A vulnerability in Grav before version 9.1.8 allows arbitrary file write via the Form plugin's process.save.filename parameter. Validation before Twig processing is not re-applied after rendering, enabling attackers to bypass checks and write files, including PHP webshells, to the web root or other sensitive directories.

Grav v2.0.0 contains a cross-site scripting vulnerability, fixed in 2.0.1. The XSS blueprint validator (Security::detectXss()) runs on raw page content before Twig processing. When Twig content processing is enabled (twig_content.process_enabled: true), an attacker with page-write API permission can use Twig's string concatenation operator (~) to dynamically construct event handler names, dangerous tag names, or dangerous protocols at render time (e.g. {% set x = "on" ~ "error" %}). The validator sees only the harmless Twig expression and allows the content, but after Twig rendering the output (rendered via {{ page.content|raw }}) contains an active payload such as <img src=1 onerror=alert(1)>, executing arbitrary JavaScript in visitors' browsers.

Grav 2.0.1 contains a decompression-bomb size-cap bypass in ZipArchiver and GPM\Installer. An attacker can supply a crafted ZIP archive with forged small entry sizes that bypass the limit, while extraction writes the actual much larger content, leading to disk or inode exhaustion.

A vulnerability in Grav prior to version 2.0.0 allows an authenticated admin.super user to crash the system or fill the disk by uploading a specially crafted ZIP archive via the Direct Install tool. The issue stems from the unZip function lacking limits on uncompressed size, entry count, or directory depth.

Grav prior to 2.0.0-rc.9 contains a stored XSS vulnerability via the Markdown image style attribute. The incomplete fix for CVE-2026-42841 leaves the MediaObjectTrait::style method reachable through the same excerpt-action pipeline, allowing an editor to save unsanitized image style parameters.

A vulnerability in Grav allows an authenticated administrator with backup permissions to download a ZIP archive containing the full Grav installation root, including user/accounts/admin.yaml with the administrator password hash and user/config with site configuration. The issue is fixed in version 1.7.53.

Grav, a file-based web platform, contains a vulnerability allowing an unauthenticated attacker to exhaust server memory and CPU by requesting oversized image derivatives. The issue is in the `Grav::fallbackUrl` mechanism, which passes request parameters to ImageMedium magic actions without dimension or pixel limits.

Grav, a file-based web platform built in PHP, is vulnerable to a server side template injection (SSTI) attack. Version 1.7.42 and later have a flaw in the `isDangerousFunction()` which allows the execution of malicious code by prepending a double backslash (`\`).