Description
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.
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 |
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-rfpc-qcw5-3pc4 |
Advisories 1
- openSUSE-SU-2026:12371-1 python313-filelock-4.2.4-1.1 on GA media SUSE / openSUSE Security Updates · Oct 31, 2026