Overview
CVE-2025-13397 identifies a security vulnerability affecting mrubyc versions up to 3.4. This vulnerability, classified as low severity, involves a null pointer dereference issue within the mrbc_raw_realloc function located in the src/alloc.c file. Successful exploitation requires local access. This article provides a comprehensive overview of the vulnerability, its potential impact, and steps to mitigate the risk.
Technical Details
The vulnerability stems from improper handling of the ptr argument within the mrbc_raw_realloc function. Malicious manipulation of this argument can lead to the function attempting to dereference a null pointer, resulting in a program crash or other unexpected behavior. The specific patch addressing this issue is identified by the commit hash 009111904807b8567262036bf45297c3da8f1c87 on the mrubyc GitHub repository.
Affected Code Snippet (from src/alloc.c):
// Example of potentially vulnerable code (simplified)
void* mrbc_raw_realloc(mrbc_context *ctx, void *ptr, size_t size) {
// ... potentially faulty logic with ptr ...
void* new_ptr = realloc(ptr, size);
// ... usage of ptr after potential invalidation ...
return new_ptr;
}
CVSS Analysis
The vulnerability has a CVSS v3.x score of 3.3, indicating a low severity. The CVSS vector is likely something similar to AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L, meaning:
- Attack Vector (AV): Local – The attacker requires local access to the system.
- Attack Complexity (AC): Low – The conditions for successful exploitation are easily met.
- Privileges Required (PR): Low – The attacker requires only basic user privileges.
- User Interaction (UI): None – No user interaction is required for exploitation.
- Scope (S): Unchanged – The vulnerability impacts only the vulnerable component.
- Confidentiality Impact (C): None – There is no impact on confidentiality.
- Integrity Impact (I): None – There is no impact on integrity.
- Availability Impact (A): Low – There is a potential for a denial-of-service (DoS) condition.
Possible Impact
While the severity is low, the vulnerability can lead to a denial-of-service (DoS) condition if successfully exploited. A local attacker could potentially cause the mrubyc application to crash by triggering the null pointer dereference. The impact is limited to availability, as there is no compromise of confidentiality or integrity. However, in embedded systems or critical infrastructure relying on mrubyc, even a low-severity DoS can have significant consequences.
Mitigation/Patch Steps
The recommended mitigation is to apply the patch identified by commit 009111904807b8567262036bf45297c3da8f1c87 from the mrubyc GitHub repository. This patch addresses the improper handling of the ptr argument in mrbc_raw_realloc, preventing the null pointer dereference. Users of mrubyc versions up to 3.4 should update their installations or apply the patch manually. Monitor the mrubyc project for official releases containing this fix.
# Example (Conceptual - Refer to official mrubyc documentation)
git apply 009111904807b8567262036bf45297c3da8f1c87.patch
