CVE-2026-65062 in Data::SortedSet::Shared
Summary
by MITRE • 07/21/2026
Data::SortedSet::Shared versions before 0.03 for Perl create a world-readable mmap backing file and open it without O_EXCL or O_NOFOLLOW.
The segment is created in sortedset.h with open(path, O_RDWR|O_CREAT, 0666). The mode is 0666, so under the default umask 022 the file is created mode 0644 (world-readable). O_NOFOLLOW is absent, so a symlink planted at the path is followed, and O_EXCL is absent, so the open silently uses a pre-planted file instead of failing.
A "Shared" segment naturally lives in a shared directory such as /tmp or /dev/shm, where any local user can read the IPC payloads stored in the world-readable segment, and a pre-planted file or symlink at the path lets a local attacker win a pre-creation race or redirect the open.
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Analysis
by VulDB Data Team • 07/21/2026
The vulnerability in Data::SortedSet::Shared versions prior to 003 presents a critical security flaw rooted in improper file system access controls and race condition exploitation opportunities. This Perl module creates memory-mapped files for shared data structures without implementing adequate security measures during file creation, fundamentally compromising the integrity and confidentiality of inter-process communication mechanisms. The implementation directly violates established security principles by creating world-readable files with predictable paths in shared system directories, exposing sensitive data to unauthorized local users who can access the underlying memory segments through standard file operations.
The technical implementation flaw manifests in the file creation call within sortedset.h using open(path, O_RDWR|O_CREAT, 0666) without proper security flags. This approach creates a fundamental vulnerability where the default umask of 022 results in files with mode 0644, making them world-readable and accessible to any local user on the system. The absence of O_EXCL flag means that if a malicious user pre-creates a file at the target path, the module will silently open and use that existing file instead of failing as expected, while the lack of O_NOFOLLOW prevents symlink traversal attacks from being properly mitigated. This combination creates multiple attack vectors that can be exploited by local adversaries to gain unauthorized access to shared memory segments containing sensitive data.
The operational impact of this vulnerability extends beyond simple information disclosure to encompass potential privilege escalation and data manipulation scenarios. Attackers can leverage the race condition inherent in the file creation process to pre-place malicious files or symlinks at the target path, effectively redirecting the module's memory mapping to arbitrary locations. This capability allows adversaries to read sensitive data from shared segments, potentially including credentials, application state information, or other confidential payloads stored within these memory-mapped structures. The vulnerability particularly affects systems where the module operates in shared directories like /tmp or /dev/shm, which are commonly used for inter-process communication and temporary storage, making it a significant concern for multi-user environments.
The security implications align with CWE-732: Incorrect Permission Assignment for Critical Resource and CWE-362: Concurrent Execution using Shared Resource with Unlocked Critical Section, while also demonstrating characteristics of ATT&CK technique T1059.007: Command and Scripting Interpreter: Python, which could be leveraged by attackers to exploit the shared memory access patterns. Mitigation strategies should prioritize updating to version 0.03 or later where proper file creation flags are implemented, specifically including O_EXCL to prevent race conditions and O_NOFOLLOW to avoid symlink attacks. Additionally, system administrators should consider restricting access to shared directories, implementing proper umask settings, and monitoring for unauthorized file creation in critical temporary locations. The module's design should also enforce stricter permission controls during memory mapping initialization, ensuring that sensitive data remains protected from unauthorized local access and preventing attackers from exploiting the predictable file creation patterns inherent in the vulnerable implementation.
The vulnerability represents a classic example of insufficient input validation and improper privilege management in system-level operations, where the assumption that all users have equal access to shared resources leads to security breaches. This flaw demonstrates how seemingly simple file creation operations can create substantial attack surfaces when proper security controls are omitted from the implementation. The impact is particularly severe because it affects data confidentiality within inter-process communication mechanisms and can be exploited without requiring special privileges beyond local system access, making it a significant concern for any application relying on shared memory segments for data exchange.