CVE-2024-4040
A server side template injection vulnerability in CrushFTP in all versions before 10.7.1 and 11.1.0 on all platforms allows unauthenticated remote attackers to…
Critical
Known exploited
- Severity
- 10.0 / 10
- Critical · CVSS 3.1
- Exploit chance (EPSS)
- 99.54%
- Chance of exploitation in the next 30 days. Higher than 99.95% of scored vulnerabilities.
- Known exploited
- Yes
- In CISA's catalog since Apr 24, 2024
- Weakness
- CWE-1336 Improper Neutralization of Special Elements Used in a Template Engine
- CWE-94 Improper Control of Generation of Code ('Code Injection')
- Fix
- None yet
- No fixed version published
Exploited in the wild. CrushFTP VFS Sandbox Escape Vulnerability (CrushFTP CrushFTP). Required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable. Due for U.S. federal agencies by May 1, 2024.
Description
A server side template injection vulnerability in CrushFTP in all versions before 10.7.1 and 11.1.0 on all platforms allows unauthenticated remote attackers to read files from the filesystem outside of the VFS Sandbox, bypass authentication to gain administrative access, and perform remote code execution on the server.
How to fix
No fixed version has been published yet. Until one is, remove or replace the package, or turn off or isolate the affected feature. This page updates when a fix ships.
Severity breakdown
CVSS 3.1 10.0
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Weakness
CWE-1336: Improper Neutralization of Special Elements Used in a Template Engine
The product uses a template engine to insert or process externally-influenced input, but it does not neutralize or incorrectly neutralizes special elements or syntax that can be interpreted as template expressions or other code directives when processed by the engine.
How to prevent it
- Architecture and Design: Choose a template engine that offers a sandbox or restricted mode, or at least limits the power of any available expressions, function calls, or commands.
- Implementation: Use the template engine's sandbox or restricted mode, if available.
CWE-94: Improper Control of Generation of Code ('Code Injection')
The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.
How to prevent it
- Architecture and Design: Refactor your program so that you do not have to dynamically generate code.
- Architecture and Design: Run your code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which code can be executed by your product. Examples include the Unix chroot jail and AppArmor. In general, managed code may provide some protection. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of your application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails.
- Implementation: Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. To reduce the likelihood of code injection, use stringent allowlists that limit which constructs are allowed. If you are dynamically constructing code that invokes a function, then verifying that the input is alphanumeric might be insufficient. An attacker might still be able to reference a dangerous function that you did not intend to allow, such as system(), exec(), or exit().
- Testing: Use dynamic tools and techniques that interact with the product using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The product's operation may slow down, but it should not become unstable, crash, or generate incorrect results.
- Operation: Run the code in an environment that performs automatic taint propagation and prevents any command execution that uses tainted variables, such as Perl's "-T" switch. This will force the program to perform validation steps that remove the taint, although you must be careful to correctly validate your inputs so that you do not accidentally mark dangerous inputs as untainted (see CWE-183 and CWE-184).
- Operation: Run the code in an environment that performs automatic taint propagation and prevents any command execution that uses tainted variables, such as Perl's "-T" switch. This will force the program to perform validation steps that remove the taint, although you must be careful to correctly validate your inputs so that you do not accidentally mark dangerous inputs as untainted (see CWE-183 and CWE-184).
- Implementation: For Python programs, it is frequently encouraged to use the ast.literal_eval() function instead of eval, since it is intentionally designed to avoid executing code. However, an adversary could still cause excessive memory or stack consumption via deeply nested structures [REF-1372], so the python documentation discourages use of ast.literal_eval() on untrusted data [REF-1373].
References
Advisories
Fixes and patches
Exploits and evidence
Other links
Timeline
- Published
- Added to CISA's Known Exploited Vulnerabilities catalog
- Remediation due for U.S. federal agencies
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-27vj-qcqg-25rc fsspec: Server-Side Template Injection in ReferenceFileSystem leads to Remote Code Execution | High | Same weakness, CWE-1336 |
| DRUPAL-CONTRIB-2026-175 The Webform module allows site builders to create forms, collect submissions, and render submitted values in configurable formats. | Critical | Same weakness, CWE-1336 |
| CVE-2026-75650 Adobe Commerce | Improper Neutralization of Special Elements Used in a Template Engine (CWE-1336) | Critical Known exploited | Same weakness, CWE-1336 |
| GHSA-73mf-m39p-wpm9 Yamcs vulnerable to Remote Code Execution via instance-template argument YAML injection (createInstance) | Critical | Same weakness, CWE-1336 |
| GHSA-6wvf-77m9-58rm LiteLLM vulnerable to server-side template injection in the /prompts/test endpoint | Critical | Same weakness, CWE-1336 |
| GHSA-x67c-8pwr-m8g3 SiYuan: Second-order SSTI to arbitrary SQL via attribute-view template column (queryBlocks): malicious imported package executes SQL on victim kernel | High | Same weakness, CWE-1336 |
| GHSA-2c4f-86xc-cr74 Grav: XSS Blueprint Validation Bypass via Twig String Concatenation | Medium | Same weakness, CWE-1336 |
| GHSA-65p8-9433-jpcp YesWiki: Authenticated (Admin) Server-Side Template Injection to Remote Code Execution via Bazar Semantic Templates | High | Same weakness, CWE-1336 |
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