CVE-2025-27531: Apache InLong Information Disclosure Flaw

CVE-2025-27531 Overview

CVE-2025-27531 is a critical Deserialization of Untrusted Data vulnerability affecting Apache InLong, a widely-used one-stop data integration framework providing automatic, safe, reliable, and high-performance data transmission capabilities. The vulnerability enables authenticated attackers to read arbitrary files on the server by exploiting a parameter double-writing technique during the deserialization process.

This insecure deserialization flaw (CWE-502) affects Apache InLong versions from 1.13.0 through versions before 2.1.0. Organizations utilizing Apache InLong for data streaming and integration should prioritize immediate remediation to prevent potential data exfiltration and unauthorized access to sensitive system files.

Critical Impact

Authenticated attackers can exploit this deserialization vulnerability to read arbitrary files on vulnerable Apache InLong instances, potentially exposing sensitive configuration data, credentials, and other confidential information.

Affected Products

• Apache InLong versions 1.13.0 through 2.0.x
• Apache InLong deployments utilizing affected deserialization components
• Systems running unpatched Apache InLong data integration pipelines

Discovery Timeline

• 2025-06-06 - CVE-2025-27531 published to NVD
• 2025-06-23 - Last updated in NVD database

Technical Details for CVE-2025-27531

Vulnerability Analysis

The vulnerability exists within Apache InLong's data processing components where user-supplied input is deserialized without adequate validation. Insecure deserialization occurs when an application deserializes data from untrusted sources without properly verifying the integrity and authenticity of the serialized objects. In this case, the flaw allows attackers to craft malicious serialized objects that, when processed by the vulnerable InLong instance, can be manipulated to read arbitrary files from the underlying file system.

The attack leverages a "double writing" technique on parameters, which allows the attacker to bypass security controls and inject malicious payloads into the deserialization process. This technique involves manipulating request parameters in a way that causes the application to process attacker-controlled data during object reconstruction.

Root Cause

The root cause of CVE-2025-27531 lies in insufficient input validation and sanitization during the deserialization of user-controlled data within Apache InLong. The application fails to properly validate serialized object data before reconstructing objects, allowing malicious payloads to be processed. Additionally, the parameter double-writing technique indicates inadequate handling of duplicate or repeated parameters in HTTP requests, enabling attackers to bypass initial security checks.

Attack Vector

The vulnerability is exploitable over the network, requiring authentication to access the vulnerable endpoints. An authenticated attacker can craft specially formatted HTTP requests containing malicious serialized objects with double-written parameters. When the Apache InLong server processes these requests, the deserialization routine reconstructs the malicious objects, which then execute file read operations on the server's file system. This allows the attacker to retrieve arbitrary files, potentially including configuration files, database credentials, private keys, and other sensitive data.

The attack does not require user interaction and can be automated once valid authentication credentials are obtained. The exploitation complexity is considered low, as the attack can be performed with standard HTTP client tools once the vulnerable endpoint and parameter manipulation technique are understood.

Detection Methods for CVE-2025-27531

Indicators of Compromise

• Unusual HTTP requests to Apache InLong endpoints containing duplicate or repeated parameters
• Log entries showing deserialization errors or unexpected object types being processed
• File access attempts to sensitive system files from the Apache InLong process
• Abnormal data transmission patterns indicating file content exfiltration

Detection Strategies

• Monitor Apache InLong application logs for deserialization exceptions and error messages
• Implement network intrusion detection rules to identify requests with suspicious parameter patterns
• Deploy file integrity monitoring on sensitive configuration files and directories
• Enable audit logging for file system access by the InLong service account
• Review web application firewall logs for blocked serialization-related attack patterns

Monitoring Recommendations

• Configure alerting for repeated failed authentication attempts followed by successful logins to InLong endpoints
• Implement behavioral analysis to detect unusual file read patterns from the InLong application
• Monitor outbound network traffic from InLong servers for signs of data exfiltration
• Establish baseline metrics for normal InLong operation and alert on deviations

How to Mitigate CVE-2025-27531

Immediate Actions Required

• Upgrade Apache InLong to version 2.1.0 or later immediately
• Audit existing deployments to identify all instances running vulnerable versions (1.13.0 to 2.0.x)
• Review access logs for evidence of exploitation attempts
• Restrict network access to Apache InLong management interfaces to trusted networks only
• Rotate any credentials or secrets that may have been exposed through arbitrary file read

Patch Information

Apache has addressed this vulnerability in Apache InLong version 2.1.0. Users should upgrade to this version or later to fully remediate the vulnerability. Detailed information about the security fix is available through the Apache Mailing List Discussion and the Openwall OSS-Security Update.

Workarounds

• Implement network segmentation to isolate Apache InLong instances from untrusted networks
• Deploy a web application firewall (WAF) with rules to block requests containing suspicious serialized data patterns
• Enforce strict authentication controls and limit user privileges to minimize potential exposure
• Consider disabling or restricting access to vulnerable endpoints until patching can be completed

# Configuration example - Network restriction for Apache InLong
# Add to firewall rules to restrict access to InLong management ports
iptables -A INPUT -p tcp --dport 8083 -s trusted_network_cidr -j ACCEPT
iptables -A INPUT -p tcp --dport 8083 -j DROP

# Verify Apache InLong version
./bin/inlong-manager-web.sh version