CVE-2026-2597 in Crypt::SysRandom::XS
Summary
by MITRE • 02/27/2026
Crypt::SysRandom::XS versions before 0.010 for Perl is vulnerable to a heap buffer overflow in the XS function random_bytes().
The function does not validate that the length parameter is non-negative. If a negative value (e.g. -1) is supplied, the expression length + 1u causes an integer wraparound, resulting in a zero-byte allocation. The subsequent call to chosen random function (e.g. getrandom) passes the original negative value, which is implicitly converted to a large unsigned value (typically SIZE_MAX). This can result in writes beyond the allocated buffer, leading to heap memory corruption and application crash (denial of service).
In common usage, the length argument is typically hardcoded by the caller, which reduces the likelihood of attacker-controlled exploitation. Applications that pass untrusted input to this parameter may be affected.
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Analysis
by VulDB Data Team • 03/11/2026
The vulnerability identified as CVE-2026-2597 affects Crypt::SysRandom::XS Perl module versions prior to 0.010, presenting a critical heap buffer overflow condition within the random_bytes() XS function. This flaw stems from inadequate input validation mechanisms that fail to verify the non-negativity of the length parameter, creating a dangerous scenario where malicious input can trigger unintended memory behavior. The vulnerability manifests when a negative integer value such as -1 is passed to the function, which then undergoes arithmetic operations that result in unexpected memory allocation patterns.
The technical exploitation occurs through integer wraparound behavior where the expression length + 1u transforms a negative input into a zero-byte allocation, followed by subsequent operations that pass the original negative value as an unsigned integer. This conversion typically results in extremely large values approaching SIZE_MAX, causing the underlying random number generation functions to attempt writes beyond the allocated buffer boundaries. The heap memory corruption that ensues can lead to application crashes and denial of service conditions, fundamentally compromising system stability and availability. This type of vulnerability aligns with CWE-121, heap-based buffer overflow, and represents a classic example of improper input validation leading to memory safety issues.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable more sophisticated attacks depending on the application context. While the typical usage pattern involves hardcoded length parameters that reduce exploitation likelihood, applications that accept untrusted input directly into the random_bytes() function become vulnerable to malicious manipulation. Attackers could exploit this by crafting negative length values to cause memory corruption in applications that rely on this module for cryptographic operations or random data generation. The vulnerability demonstrates how seemingly minor input validation gaps can create significant security risks in cryptographic libraries where memory safety is paramount for preventing potential information disclosure or arbitrary code execution scenarios.
Mitigation strategies should focus on immediate module version upgrades to 0.010 or later, which contain proper input validation mechanisms that prevent negative length parameters from being processed. Organizations should also implement comprehensive input validation checks in their application code that interfaces with this module, ensuring that all user-supplied length parameters are validated before being passed to cryptographic functions. Additionally, runtime monitoring and memory protection mechanisms such as address space layout randomization and stack canaries should be enabled to reduce exploitability. The vulnerability highlights the importance of adhering to secure coding practices and following ATT&CK framework considerations for input validation and memory safety, particularly in cryptographic components that handle sensitive operations. System administrators should also consider implementing automated patch management processes to ensure timely deployment of security updates across all affected systems.