CVE-2025-27151: Redis Buffer Overflow Vulnerability

CVE-2025-27151 Overview

CVE-2025-27151 is a stack-based buffer overflow vulnerability affecting Redis, the popular open-source in-memory database that persists data to disk. The vulnerability exists in the redis-check-aof utility, which is used to check and repair Append Only File (AOF) files in Redis deployments. The flaw stems from improper use of memcpy with strlen(filepath) when copying a user-supplied file path into a fixed-size stack buffer, allowing an attacker to overflow the stack and potentially achieve arbitrary code execution.

Critical Impact

Successful exploitation of this stack-based buffer overflow could allow attackers to execute arbitrary code on systems running vulnerable versions of Redis, potentially leading to complete system compromise.

Affected Products

• Redis versions 7.0.0 through 7.4.x
• Redis versions 8.0.0 through 8.0.1
• Systems utilizing the redis-check-aof utility with user-controlled file paths

Discovery Timeline

• 2025-05-29 - CVE-2025-27151 published to NVD
• 2025-12-23 - Last updated in NVD database

Technical Details for CVE-2025-27151

Vulnerability Analysis

The vulnerability is classified as CWE-20 (Improper Input Validation), though the root cause is a classic stack-based buffer overflow pattern. The redis-check-aof utility fails to properly validate the length of user-supplied file paths before copying them into a fixed-size stack buffer. When a file path exceeds the buffer's allocated size, the excess data overwrites adjacent stack memory, including potentially critical values such as return addresses and saved frame pointers.

This type of memory corruption vulnerability is particularly dangerous because stack overflows can be leveraged to hijack program control flow. An attacker who can control the overwritten return address can redirect execution to attacker-controlled code or existing code gadgets within the process memory space.

Root Cause

The root cause lies in the unsafe use of memcpy combined with strlen(filepath) without bounds checking. The code copies the entire user-supplied file path into a fixed-size stack buffer without verifying that the path length does not exceed the buffer capacity. This violates secure coding principles that require explicit bounds checking before memory copy operations.

The fix, implemented in commit 643b5db235cb82508e72f11c7b4bbfc7dc39be56, addresses this by implementing proper bounds validation to ensure the file path length does not exceed the allocated buffer size before performing the copy operation.

Attack Vector

The attack vector is network-based according to the vulnerability assessment. An attacker can exploit this vulnerability by providing an overly long file path argument to the redis-check-aof utility. The attack does not require authentication or user interaction, making it particularly accessible to attackers.

In practical exploitation scenarios, an attacker would craft a malicious file path that:

1. Exceeds the fixed buffer size allocated on the stack
2. Contains carefully positioned values to overwrite the return address
3. Includes shellcode or ROP gadgets to achieve code execution

For detailed technical information about the vulnerability and its exploitation, refer to the GitHub Security Advisory GHSA-5453.

Detection Methods for CVE-2025-27151

Indicators of Compromise

• Unusual invocations of redis-check-aof with abnormally long file path arguments
• Crash dumps or core files from the redis-check-aof process indicating stack corruption
• Process execution anomalies following redis-check-aof invocations
• Memory access violations or segmentation faults in Redis utilities

Detection Strategies

• Monitor for redis-check-aof process invocations with file path arguments exceeding normal operational lengths
• Implement application-level logging to capture command-line arguments passed to Redis utilities
• Deploy endpoint detection solutions capable of identifying stack-based buffer overflow exploitation attempts
• Utilize memory protection mechanisms such as stack canaries and ASLR to detect and prevent exploitation

Monitoring Recommendations

• Enable audit logging for all Redis utility executions in production environments
• Configure alerting for abnormal process behavior following redis-check-aof execution
• Monitor system logs for segmentation faults or access violations related to Redis processes
• Implement file integrity monitoring on Redis binary and utility files

How to Mitigate CVE-2025-27151

Immediate Actions Required

• Upgrade Redis to version 8.0.2 or later immediately
• Restrict access to the redis-check-aof utility to trusted administrators only
• Implement network segmentation to limit exposure of Redis infrastructure
• Review access controls on systems where Redis utilities are deployed

Patch Information

Redis has released version 8.0.2 which addresses this vulnerability. The fix was implemented in commit 643b5db235cb82508e72f11c7b4bbfc7dc39be56. Organizations should upgrade to the patched version as soon as possible.

• GitHub Redis Release 8.0.2
• GitHub Redis Commit Update

Workarounds

• Restrict execution permissions for redis-check-aof to root or dedicated service accounts only
• Implement wrapper scripts that validate file path lengths before passing them to redis-check-aof
• Use containerization or sandboxing to isolate Redis utilities from critical system components
• Disable or remove redis-check-aof if AOF functionality is not required in your deployment

# Restrict redis-check-aof execution permissions
chmod 700 /usr/local/bin/redis-check-aof
chown root:root /usr/local/bin/redis-check-aof

# Verify Redis version after upgrade
redis-server --version