External risk intelligence

Apache Arrow Rust Out-of-Bounds Read Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.1)

CVE-2026-111959

This vulnerability exists in the Apache Arrow Rust crate, which is a software library or dependency used by developers to build applications. It is not a standalone network service, appliance, or edge gateway. While it may be incorporated into internet-facing applications, the library itself is typically embedded within internal software components rather than being directly exposed to the public internet.

Out-of-bounds Read

Halo Surface Signal: 2 out of 5 — less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This advisory concerns a critical vulnerability in the Apache Arrow Rust crate, a component used in data processing. The issue allows for out-of-bounds reads, potentially leading to unauthorized data access or denial of service. The main concern is confirming if this library is used within our environment and if so, to what extent it might be exposed.

Reading beyond data boundaries is possible.
Critical flaw impacting data integrity and availability.
Confirm relevance and exposure within our systems.

Attack Path

How an attacker could exploit the issue

An attacker can exploit this vulnerability by providing specially crafted input to a system that uses the affected Apache Arrow Rust crate. This input could trigger an out-of-bounds read when the system attempts to process RunEndEncoded arrays, potentially leading to information disclosure or denial of service.

Requires vulnerable software dependency.
Triggered by improper array validation.
Risk of data exposure or service crash.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow an attacker to read data beyond the intended boundaries of an array within the Arrow Rust crate when processing RunEndEncoded arrays. This could potentially expose sensitive information or lead to unexpected program behavior.

Arbitrary memory data at risk.
Network access can trigger out-of-bounds reads.
Potential for information disclosure.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability resides within the Apache Arrow Rust crate, a common software library used by developers. Responsibility for addressing this issue likely falls to the teams that integrate this library into their applications, such as application development or platform teams. The first practical step is to identify all instances where this crate is used, determine their reachability and criticality, and then assign ownership for remediation planning.

Application owners should manage remediation.
Verify all usages and business criticality.
Plan updates during maintenance windows.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

Free EASM Trial See How Signal Works

Frequently asked questions

What is the Apache Arrow Rust crate?

The Apache Arrow Rust crate is a collection of software libraries that developers use to process large datasets efficiently. It provides the building blocks for memory-efficient data structures, often used in analytics, database engines, and high-performance computing applications to manage data movement between different systems.

What does the CVE-2026-111959 out-of-bounds read mean?

This vulnerability, classified as CWE-125 (Out-of-bounds Read), occurs when a program accesses memory outside the intended buffer. In this case, the code fails to properly validate 'RunEndEncoded' arrays, allowing the software to read memory that shouldn't be accessed. This can cause the application to leak data or crash.

How is this Apache Arrow vulnerability triggered?

The flaw is triggered when the affected software processes a specifically crafted RunEndEncoded array. If the system does not handle this input correctly, it attempts to read past the end of an array. Note that standard, correctly formatted arrays used in typical operations do not trigger this error; it requires malformed data to exploit the memory access boundary.

Is my system at risk according to Halo Surface Signal?

Halo Surface Signal identifies this as an 'Unlikely' direct risk because the Apache Arrow Rust crate is a library integrated into larger applications, not a standalone network service. While it might be part of an internet-facing tool, the library itself is typically embedded deep within software, meaning external network exposure depends entirely on how your specific applications use it.

What is the first step to address CVE-2026-111959?

Begin by auditing your software inventory to locate applications that rely on the Apache Arrow Rust crate. Once identified, confirm the specific versions in use. If you are using any affected version (33.0.0 through 60.0.0, excluding patched releases), coordinate with your development team to plan an update to the secure versions, such as 60.1.0 or 59.3.2.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.