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CVE-2026-112912— filelock: Symlink swap during SoftFileLock's writability check leaks whether a path exists and is writable by the lock taker

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 是一个与平台无关的 Python 文件锁工具。在版本 3.32.6 至 4.2.1 期间，SoftFileLock 在执行针对缺少所有者写入权限节点的 可写性条件检查时，可能会跟随被交换的符号链接。在遵循该符号链接的平台和目录配置下，同一系统中的其他本地用户可通过观察锁获取结果，推断出目标路径是否存在以及是否可写。该问题已在版本 4.2.1 中修复。

CVSS 2.5 · Low
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I. Basic Information for CVE-2026-112912

Vulnerability Information
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Vulnerability Title
filelock: Symlink swap during SoftFileLock's writability check leaks whether a path exists and is writable by the lock taker
Source: CVE Program / CVE List V5
Vulnerability Description
filelock is a platform-independent file lock for Python. From 3.32.6 until 4.2.1, SoftFileLock can follow a swapped symbolic link during the conditional os.access writability check for a node without its owner-write bit, allowing another local user on a platform and directory configuration that follows the link to infer whether a chosen path exists and is writable from the observable acquisition result. 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:L/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
在文件访问前对链接解析不恰当(链接跟随)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
tox-dev filelock >= 3.32.6, < 4.2.1 -

II. Public POCs for CVE-2026-112912

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III. Intelligence Information for CVE-2026-112912

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Other References for CVE-2026-112912 (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-2026-112935 4.7 MEDIUM filelock: SoftFileLock stale-lock break removes a live lock file on a reused inode number
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

IV. Related Vulnerabilities

Same product: filelock
Same vendor: tox-dev
Same weakness: CWE-59

V. Comments for CVE-2026-112912

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