CVE-2026-49146 in App::Ack
Summary
by MITRE • 07/08/2026
App::Ack versions before 3.10.0 for Perl allow memory exhaustion via an unbounded context value in a project .ackrc.
ack searches up the directory hierarchy from the current directory for a project .ackrc and loads its options. The -B and -C context options accepted any positive integer, and ack sized the before-context buffer to that value, so a project .ackrc setting --before-context=100000000 made ack allocate a buffer of 100 million elements.
A project .ackrc committed to an untrusted repository can abort ack with an out-of-memory condition.
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Analysis
by VulDB Data Team • 07/08/2026
The vulnerability in App::Ack versions prior to 3.10.0 represents a classic denial of service through resource exhaustion, specifically targeting memory allocation mechanisms within the Perl-based text search utility. This flaw stems from inadequate input validation and buffer sizing logic that fails to impose reasonable limits on user-defined context values. The issue manifests when ack processes configuration files located in project directories, particularly the .ackrc file that contains various operational parameters including context settings for before and after text display around matching lines.
The technical implementation of this vulnerability exploits the directory traversal mechanism inherent in ack's operation where it recursively searches upward through directory structures to locate project-specific configuration files. When a malicious or compromised .ackrc file contains an excessively large value for the --before-context option, typically set to values like 100000000, the application blindly accepts this parameter without validation. This behavior directly violates security principles of input sanitization and resource management, creating a scenario where memory allocation scales linearly with user-provided input rather than being bounded by reasonable operational constraints.
The operational impact of this vulnerability extends beyond simple denial of service to potentially compromise system stability and availability within environments where ack is used for code scanning or automated text processing. When an attacker places a malicious .ackrc file in a repository or shared directory structure, any user executing ack in that context will trigger the memory exhaustion condition, causing the application to terminate abnormally. This vulnerability particularly affects continuous integration systems, automated code review processes, and collaborative development environments where multiple developers may be working with untrusted code repositories.
The root cause of this issue aligns with CWE-770, which specifically addresses allocation of resources without proper limits or bounds checking. The vulnerability demonstrates poor resource management practices where the application fails to implement reasonable constraints on user-supplied parameters that directly influence memory consumption. From an attack perspective, this represents a low-effort, high-impact vector that leverages the legitimate functionality of configuration file processing to achieve malicious memory exhaustion. The ATT&CK framework categorizes this under privilege escalation and denial of service techniques, as the vulnerability can be exploited by any user with write access to project directories, potentially allowing for system-wide availability disruption.
Mitigation strategies should focus on implementing strict parameter validation and resource boundary enforcement within the application's configuration processing pipeline. Version 3.10.0 addressed this issue through the introduction of maximum value limits for context parameters, preventing arbitrary memory allocation while maintaining functional utility. System administrators should ensure all ack installations are updated to versions containing these security patches, and organizations should implement automated scanning processes to identify potentially malicious .ackrc files in repository structures. Additionally, defensive programming practices should be enforced throughout the codebase to validate all user-provided inputs against expected ranges and allocate memory only after thorough parameter verification to prevent similar vulnerabilities from emerging in other application components.