CVE-2026-112939Medium· 4.7▾ TwilightPoC availablefilelock is a platform-independent file lock for Python. From 3.22.0 until 4.2.1, SoftFileLock can trust a forged process identifier in a marker that an attacker can modify but cannot remove, allowing an authorized contender such as anot…
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 25.9 · likelihood 0 · exploitation 12
A public proof-of-concept already exists for this vulnerability — see Exploit availability below.
Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake. The CVSS score shown above comes from the assigning CNA record, not NVD.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via CVEORG
Exploit / PoC code exists
filelock is a platform-independent file lock for Python. From 3.22.0 until 4.2.1, SoftFileLock can trust a forged process identifier in a marker that an attacker can modify but cannot remove, allowing an authorized contender such as another process of the holder's account or root to act as a confused deputy, remove the live marker, and admit another holder. This issue is fixed in version 4.2.1.
filelock >= 3.22.0, < 4.2.1Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Field changes observed since this record was first indexed.
Connected by shared product, vendor, weakness, or advisory.
CVE-2026-112906Medium· 4.7filelock: SoftFileLock evicts a fresh lock file whose watched age another local user's pre-dated file passed on through inode reuse
CVE-2026-112912Low· 2.5filelock: Symlink swap during SoftFileLock's writability check leaks whether a path exists and is writable by the lock taker
CVE-2026-112915Medium· 5.5filelock ReadWriteLock: a crafted lock database makes every acquire stall or hang regardless of timeout
CVE-2026-112909Medium· 6.1filelock: UnixFileLock truncates and chmods any regular file another user renames or hard-links onto the lock path
CVE-2026-112911Medium· 6.3filelock: StrictSoftFileLock and SoftReadWriteLock adopt a protocol directory another user created first, losing mutual exclusion
CVE-2026-112914Medium· 5.3filelock: SoftFileLock stale-break restore follows a swapped-in symbolic link and hard-links a file of the user running the lock into the lock directory