CWE-367 vulnerabilities

Time-of-check time-of-use (toctou) race condition in Windows Kernel Memory allows an authorized attacker to elevate privileges locally.

## Vulnerability Summary **Title:** Time-of-Check-Time-of-Use (TOCTOU) Symlink Vulnerability in SoftFileLock **Affected Component:** `filelock` package - `SoftFileLock` class **File:** `src/filelock/_soft.py` lines 17-27 **CWE:** CWE-362, CWE-367, CWE-59 --- ## Description A TOCTOU race condition vulnerability exists in the `SoftFileLock` implementation of the filelock package. An attacker with local filesystem access and permission to create symlinks can exploit a race condition between the permission validation and file creation to cause lock operations to fail or behave unexpectedly. The vulnerability occurs in the `_acquire()` method between `raise_on_not_writable_file()` (permission check) and `os.open()` (file creation). During this race window, an attacker can create a symlink at the lock file path, potentially causing the lock to operate on an unintended target file or leading to denial of service. ### Attack Scenario ``` 1. Lock attempts to acquire on /tmp/app.lock 2. Permission validation passes 3. [RACE WINDOW] - Attacker creates: ln -s /tmp/important.txt /tmp/app.lock 4. os.open() tries to create lock file 5. Lock operates on attacker-controlled target file or fails ``` --- ## Impact _What kind of vulnerability is it? Who is impacted?_ This is a **Time-of-Check-Time-of-Use (TOCTOU) race condition vulnerability** affecting any application using `SoftFileLock` for inter-process synchronization. **Affected Users:** - Applications using `filelock.SoftFileLock` directly - Applications using the fallback `FileLock` on systems without `fcntl` support (e.g., GraalPy) **Consequences:** - **Silent lock acquisition failure** - applications may not detect that exclusive resource access is not guaranteed - **Denial of Service** - attacker can prevent lock file creation by maintaining symlink - **Resource serialization failures** - multiple processes may acquire "locks" simultaneously - **Unintended file operations** - lock could operate on attacker-controlled files **CVSS v4.0 Score:** 5.6 (Medium) **Vector:** CVSS:4.0/AV:L/AT:L/PR:L/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N **Attack Requirements:** - Local filesystem access to the directory containing lock files - Permission to create symlinks (standard for regular unprivileged users on Unix/Linux) - Ability to time the symlink creation during the narrow race window --- ## Patches _Has the problem been patched? What versions should users upgrade to?_ Yes, the vulnerability has been patched by adding the `O_NOFOLLOW` flag to prevent symlink following during lock file creation. **Patched Version:** Next release (commit: 255ed068bc85d1ef406e50a135e1459170dd1bf0) **Mitigation Details:** - The `O_NOFOLLOW` flag is added conditionally and gracefully degrades on platforms without support - On platforms with `O_NOFOLLOW` support (most modern systems): symlink attacks are completely prevented - On platforms without `O_NOFOLLOW` (e.g., GraalPy): TOCTOU window remains but is documented **Users should:** - Upgrade to the patched version when available - For critical deployments, consider using `UnixFileLock` or `WindowsFileLock` instead of the fallback `SoftFileLock` --- ## Workarounds _Is there a way for users to fix or remediate the vulnerability without upgrading?_ For users unable to update immediately: 1. **Avoid `SoftFileLock` in security-sensitive contexts** - use `UnixFileLock` or `WindowsFileLock` when available (these were already patched for CVE-2025-68146) 2. **Restrict filesystem permissions** - prevent untrusted users from creating symlinks in lock file directories: ```bash chmod 700 /path/to/lock/directory ``` 3. **Use process isolation** - isolate untrusted code from lock file paths to prevent symlink creation 4. **Monitor lock operations** - implement application-level checks to verify lock acquisitions are successful before proceeding with critical operations --- ## References _Are there any links users can visit to find out more?_ - **Similar Vulnerability:** CVE-2025-68146 (TOCTOU vulnerability in UnixFileLock/WindowsFileLock) - **CWE-362 (Concurrent Execution using Shared Resource):** https://cwe.mitre.org/data/definitions/362.html - **CWE-367 (Time-of-check Time-of-use Race Condition):** https://cwe.mitre.org/data/definitions/367.html - **CWE-59 (Improper Link Resolution Before File Access):** https://cwe.mitre.org/data/definitions/59.html - **O_NOFOLLOW documentation:** https://man7.org/linux/man-pages/man2/open.2.html - **GitHub Repository:** https://github.com/tox-dev/filelock --- **Reported by:** George Tsigourakos (@tsigouris007)

Memory corruption while handling sensor utility operations.

Memory corruption while processing a config call from userspace.

A path traversal vulnerability has been reported to affect several product versions. If a local attacker gains a user account, they can then exploit the vulnerability to read the contents of unexpected files or system data. We have already fixed the vulnerability in the following versions: Qfinder Pro Mac 7.13.0 and later Qsync for Mac 5.1.5 and later QVPN Device Client for Mac 2.2.8 and later

Nest is a framework for building scalable Node.js server-side applications. Versions prior to 11.1.11 have a Fastify URL encoding middleware bypass. A NestJS application is vulnerable if it uses `@nestjs/platform-fastify`; relies on `NestMiddleware` (via `MiddlewareConsumer`) for security checks (authentication, authorization, etc.), or through `app.use()`; and applies middleware to specific routes using string paths or controllers (e.g., `.forRoutes('admin')`). Exploitation can result in unauthenticated users accessing protected routes, restricted administrative endpoints becoming accessible to lower-privileged users, and/or middleware performing sanitization or validation being skipped. This issue is patched in `@nestjs/platform-fastify@11.1.11`.

IBM Concert 1.0.0 through 2.1.0 could allow a local user to escalate their privileges due to a race condition of a symbolic link.

Versa SASE Client for Windows versions released between 7.8.7 and 7.9.4 contain a local privilege escalation vulnerability in the audit log export functionality. The client communicates user-controlled file paths to a privileged service, which performs file system operations without impersonating the requesting user. Due to improper privilege handling and a time-of-check time-of-use race condition combined with symbolic link and mount point manipulation, a local authenticated attacker can coerce the service into deleting arbitrary directories with SYSTEM privileges. This can be exploited to delete protected system folders such as C:\\Config.msi and subsequently achieve execution as NT AUTHORITY\\SYSTEM via MSI rollback techniques.

BullWall Server Intrusion Protection (SIP) services are initialized after login services during system startup. A local, authenticated attacker can log in after boot and before SIP MFA is running. The SIP services do not retroactively enforce MFA or disconnect sessions that were not subject to SIP MFA. Versions 4.6.0.0, 4.6.0.6, 4.6.0.7, and 4.6.1.4 are affected. Other versions mayy also be affected. BullWall plans to improve detection method documentation.

CVE-2025-62003 is a high-severity TOCTOU race condition vulnerability in BullWall Server Intrusion Protection versions 4.6.0.0, 4.6.0.6, 4.6.0.7, and 4.

filelock is a platform-independent file lock for Python. In versions prior to 3.20.1, a Time-of-Check-Time-of-Use (TOCTOU) race condition allows local attackers to corrupt or truncate arbitrary user files through symlink attacks. The vulnerability exists in both Unix and Windows lock file creation where filelock checks if a file exists before opening it with O_TRUNC. An attacker can create a symlink pointing to a victim file in the time gap between the check and open, causing os.open() to follow the symlink and truncate the target file. All users of filelock on Unix, Linux, macOS, and Windows systems are impacted. The vulnerability cascades to dependent libraries. The attack requires local filesystem access and ability to create symlinks (standard user permissions on Unix; Developer Mode on Windows 10+). Exploitation succeeds within 1-3 attempts when lock file paths are predictable. The issue is fixed in version 3.20.1. If immediate upgrade is not possible, use SoftFileLock instead of UnixFileLock/WindowsFileLock (note: different locking semantics, may not be suitable for all use cases); ensure lock file directories have restrictive permissions (chmod 0700) to prevent untrusted users from creating symlinks; and/or monitor lock file directories for suspicious symlinks before running trusted applications. These workarounds provide only partial mitigation. The race condition remains exploitable. Upgrading to version 3.20.1 is strongly recommended.

Open OnDemand is an open-source HPC portal. Prior to versions 4.0.8 and 3.1.16, users can craft a "Time of Check to Time of Use" (TOCTOU) attack when downloading zip files to access files outside of the OOD_ALLOWLIST. This vulnerability impacts sites that use the file browser allowlists in all current versions of OOD. However, files accessed are still protected by the UNIX permissions. Open OnDemand versions 4.0.8 and 3.1.16 have been patched for this vulnerability.

Kernel or driver software installed on a Guest VM may post improper commands to the GPU Firmware to exploit a TOCTOU race condition and trigger a read and/or write of data outside the allotted memory escaping the virtual machine.

Double fetch in sandbox kernel driver in Avast/AVG Antivirus <25.3  on windows allows local attacker to escalate privelages via pool overflow.

In JetBrains ReSharper, Rider and dotTrace before 2025.2.5 local privilege escalation was possible via race condition

Manager-io/Manager is accounting software. In Manager Desktop and Server versions 25.11.1.3085 and below, a critical vulnerability permits unauthorized access to internal network resources. The flaw lies in the fundamental design of the DNS validation mechanism. A Time-of-Check Time-of-Use (TOCTOU) condition that allows attackers to bypass network isolation and access internal services, cloud metadata endpoints, and protected network segments. The Desktop edition requires no authentication; the Server edition requires only standard authentication. This issue is fixed in version 25.11.1.3086.

In wlan STA driver, there is a possible out of bounds read due to a race condition. This could lead to local information disclosure with User execution privileges needed. User interaction is not needed for exploitation. Patch ID: WCNCR00435337; Issue ID: MSV-4036.

node-tar is a Tar for Node.js. In 7.5.1, using .t (aka .list) with { sync: true } to read tar entry contents returns uninitialized memory contents if tar file was changed on disk to a smaller size while being read. This vulnerability is fixed in 7.5.2.

yt-grabber-tui is a C++ terminal user interface application for downloading YouTube content.yt-grabber-tui version 1.0 contains a Time-of-Check to Time-of-Use (TOCTOU) race condition (CWE-367) in the creation of the default configuration file config.json. In version 1.0, load_json_settings in Settings.hpp checks for the existence of config.json using boost::filesystem::exists and, if the file is missing, calls create_json_settings which writes the JSON configuration with boost::property_tree::write_json. A local attacker with write access to the application’s configuration directory (~/.config/yt-grabber-tui on Linux or the current working directory on Windows) can create a symbolic link between the existence check and the subsequent write so that the write operation follows the symlink and overwrites an attacker-chosen file accessible to the running process. This enables arbitrary file overwrite within the privileges of the application process, which can corrupt files and cause loss of application or user data. If the application is executed with elevated privileges, this could extend to system file corruption. The issue is fixed in version 1.0.1.

Creative Cloud Desktop versions 6.7.0.278 and earlier are affected by a Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability that could lead to arbitrary file system write. A low-privileged attacker could exploit the timing between the check and use of a resource, potentially allowing unauthorized modifications to files. Exploitation of this issue does not require user interaction.