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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| tox-dev | filelock | >= 3.22.0, < 4.2.1 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | python-filelock | 4.2.8-1 | — |
| Debian 13 | python-filelock | No fix yet | — |
| Debian 12 | python-filelock | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | python-filelock | No fix yet | — |
| Ubuntu 26.04 LTS | python-filelock | No fix yet | — |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 24.04 LTS | python-filelock | No fix yet | — |
| Ubuntu Pro 22.04 LTS | python-filelock | No fix yet | — |
| Ubuntu Pro 20.04 LTS | python-filelock | No fix yet | — |
| Ubuntu Pro 18.04 LTS | python-filelock | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | python-filelock | 4.2.4-1.1 | openSUSE-SU-2026:12371-1 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | python-filelock | No fix yet | — |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | py3.10-filelock | No fix yet | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | filelock | >= 3.22.0, < 4.2.1 | 4.2.1 | GHSA-fq56-3cx3-fjxp |
Advisories 1
- openSUSE-SU-2026:12371-1 python313-filelock-4.2.4-1.1 on GA media SUSE / openSUSE Security Updates · Oct 31, 2026