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CVE-2026-112935— filelock: SoftFileLock stale-lock break removes a live lock file on a reused inode number and admits two holders

Quick assessment

Affected
tox-dev filelock
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

filelock 是一个跨平台的 Python 文件锁工具。在 3.22.0 至 4.2.1 版本期间，SoftFileLock 存在以下漏洞：攻击者在读取过期的标记后释放其自身标记，随后一个诚实的竞争者会在被复用的 inode 上创建一个新的有效标记；若该新标记的修改时间不早于之前保存的观察时间，则会导致这个有效的标记被错误删除，从而使得两个持有者同时被允许访问资源。该问题已在 4.2.1 版本中修复。

CVSS 4.7 · Medium

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-112935

Vulnerability Information
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Vulnerability Title
filelock: SoftFileLock stale-lock break removes a live lock file on a reused inode number and admits two holders
Source: CVE Program / CVE List V5
Vulnerability Description
filelock is a platform-independent file lock for Python. From 3.22.0 until 4.2.1, SoftFileLock can break a stale marker after an attacker frees its own marker following the stale read, an honest contender creates a live successor on the reused inode, and the successor's modification time is not newer than the saved observation, causing the live marker to be removed and two holders to be admitted. This issue is fixed in version 4.2.1.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
检查时间与使用时间(TOCTOU)的竞争条件
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
tox-dev filelock >= 3.22.0, < 4.2.1 -

II. Public POCs for CVE-2026-112935

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III. Intelligence Information for CVE-2026-112935

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Other References for CVE-2026-112935 (4)

Same Patch Batch · tox-dev · 2026-10-20 · 13 CVEs total

CVE-2026-112940 7.1 HIGH filelock ReadWriteLock: SQLite reopens the lock database by name, so a planted symlink or
CVE-2026-112911 6.3 MEDIUM filelock: StrictSoftFileLock and SoftReadWriteLock adopt a protocol directory another user
CVE-2026-112909 6.1 MEDIUM filelock: UnixFileLock truncates and chmods any regular file another user renames or hard-
CVE-2026-112934 6.1 MEDIUM filelock: SoftReadWriteLock holder refresh writes through a hard link and hangs on a named
CVE-2026-112936 6.1 MEDIUM filelock: ReadWriteLock follows a symlink at the lock path into SQLite
CVE-2026-112937 6.1 MEDIUM filelock: ReadWriteLock on the hard-link route deletes any directory another user renames
CVE-2026-112915 5.5 MEDIUM filelock ReadWriteLock: a crafted lock database makes every acquire stall or hang regardle
CVE-2026-112914 5.3 MEDIUM filelock: SoftFileLock stale-break restore follows a swapped-in symbolic link and hard-lin
CVE-2026-112906 4.7 MEDIUM filelock: SoftFileLock evicts a fresh lock file whose watched age another local user's pre
CVE-2026-112939 4.7 MEDIUM filelock: SoftFileLock removes a live holder's marker when another user forges the PID in
CVE-2026-112941 3.3 LOW filelock: SoftReadWriteLock follows a lock tree swapped in after its first acquire and wri
CVE-2026-112912 2.5 LOW filelock: Symlink swap during SoftFileLock's writability check leaks whether a path exists

IV. Related Vulnerabilities

Same product: filelock
Same vendor: tox-dev
Same weakness: CWE-367

V. Comments for CVE-2026-112935

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