CVE-2026-25087: Apache Arrow C++ Use After Free Flaw

CVE-2026-25087 Overview

CVE-2026-25087 is a Use After Free vulnerability affecting Apache Arrow C++ versions 15.0.0 through 23.0.0. The vulnerability can be triggered when reading an Arrow IPC file with pre-buffering enabled, specifically when the IPC file contains data with variadic buffers such as Binary View and String View data. Due to improper memory management during multi-threaded IO operations, a write to a dangling pointer could occur, potentially leading to memory corruption, crashes, or denial of service conditions.

Critical Impact

This Use After Free vulnerability in Apache Arrow C++ could allow attackers to cause denial of service through memory corruption when processing maliciously crafted IPC files with pre-buffering enabled.

Affected Products

• Apache Arrow C++ versions 15.0.0 through 23.0.0
• Applications using the RecordBatchFileReader::PreBufferMetadata API call
• Systems processing untrusted Arrow IPC files with pre-buffering enabled

Discovery Timeline

• 2026-02-17 - CVE-2026-25087 published to NVD
• 2026-02-18 - Last updated in NVD database

Technical Details for CVE-2026-25087

Vulnerability Analysis

This Use After Free vulnerability (CWE-416) resides in the Apache Arrow C++ IPC file reader implementation. The flaw manifests when the RecordBatchFileReader::PreBufferMetadata function is called to enable pre-buffering, and the IPC file being processed contains columns with variadic buffers, such as Binary View or String View data types.

The vulnerability stems from improper memory lifecycle management during concurrent IO operations. When multiple threads access the pre-buffered metadata simultaneously, the temporal sequencing of these operations can create a race condition where a pointer is dereferenced after its underlying memory has been freed. The value written to the dangling pointer—a std::shared_ptr<Buffer> object—is not directly controllable by an attacker, which somewhat limits the exploitability for targeted attacks beyond denial of service.

Importantly, pre-buffering is disabled by default and must be explicitly enabled via the C++ API. Language bindings for Python, Ruby, and C GLib do not expose this functionality, meaning applications using only these bindings are not vulnerable to this issue.

Root Cause

The root cause is a memory management error in the Arrow IPC file reader's pre-buffering implementation. When processing variadic buffers in record batch columns with pre-buffering enabled, the code fails to properly synchronize memory access across multiple threads during IO operations. This results in a Use After Free condition where the application may write to memory that has already been deallocated, leading to undefined behavior.

Attack Vector

The attack vector for CVE-2026-25087 is network-based, requiring an attacker to craft a malicious Arrow IPC file containing specific variadic buffer configurations. The attack scenario involves:

1. An attacker creates a specially crafted Arrow IPC file with Binary View or String View data containing multiple variadic buffers
2. The target application ingests this malicious IPC file from an untrusted source
3. If the application has pre-buffering enabled via RecordBatchFileReader::PreBufferMetadata, the vulnerability is triggered during file reading
4. Depending on memory allocation patterns and multi-threaded IO timing, memory corruption occurs

The exploitation complexity is high due to the dependency on specific memory allocation and multi-threaded IO temporal patterns that are difficult to control externally.

Detection Methods for CVE-2026-25087

Indicators of Compromise

• Unexpected application crashes when processing Arrow IPC files, particularly those from untrusted sources
• Memory corruption errors or segmentation faults in applications using Apache Arrow C++ with pre-buffering enabled
• Abnormal memory access patterns in process logs or crash dumps referencing Arrow IPC reader components
• Presence of unusually crafted IPC files with variadic buffer structures in ingestion pipelines

Detection Strategies

• Monitor application logs for crashes or exceptions related to RecordBatchFileReader or pre-buffering operations
• Implement file validation and sandboxing for IPC files received from untrusted sources
• Use memory debugging tools such as AddressSanitizer (ASan) to detect Use After Free conditions during development and testing
• Review application code for usage of RecordBatchFileReader::PreBufferMetadata API calls

Monitoring Recommendations

• Enable application crash reporting and analyze crash dumps for patterns consistent with memory corruption
• Implement file integrity monitoring for directories containing Arrow IPC files
• Monitor system resource usage for anomalies that could indicate denial of service attempts
• Track incoming IPC files from external sources and validate their structure before processing

How to Mitigate CVE-2026-25087

Immediate Actions Required

• Upgrade Apache Arrow C++ to version 23.0.1 or later, which contains the fix for this vulnerability
• If upgrading is not immediately possible, disable pre-buffering by removing or avoiding calls to RecordBatchFileReader::PreBufferMetadata
• Review application code to identify any usage of the vulnerable pre-buffering functionality
• Implement input validation for IPC files from untrusted sources while remediation is in progress

Patch Information

Apache Arrow has released version 23.0.1 which addresses this vulnerability. The fix is tracked in GitHub Pull Request #48925. Users should upgrade to this version or later. The security advisory and additional details are available via the Apache Mailing List Thread and the OpenWall OSS Security Post.

Workarounds

• Disable pre-buffering on the IPC file reader by not calling RecordBatchFileReader::PreBufferMetadata; note this may have adverse performance consequences for applications that rely on this feature
• Restrict IPC file ingestion to trusted sources only until patching can be completed
• Implement additional input validation to reject IPC files with suspicious variadic buffer configurations
• Consider using Python, Ruby, or C GLib language bindings instead of the C++ API, as these bindings do not expose the vulnerable functionality

# Verify Apache Arrow version and check for vulnerable API usage
# Check installed Arrow version
pkg-config --modversion arrow-cpp

# Search codebase for vulnerable API usage
grep -r "PreBufferMetadata" --include="*.cpp" --include="*.h" /path/to/source

# Upgrade to patched version
# Follow your package manager or build system's process to upgrade to Arrow 23.0.1+