# CVE-2026-112915: filelock ReadWriteLock unbounded SQLite query denial of service

Source: https://junglewise.ai/threats/cve-2026-112915-filelock-is-a-platform-independent-file-lock-for-python-from-3  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-20. Updated: 2026-10-20  
License: CC BY 4.0 with a link back

CVE-2026-112915 · Severity: medium · CVSS 5.5 · Published 2026-10-20

filelock is a Python library that provides file locking across platforms. Versions 3.20.4 through 4.2.1 contain a denial-of-service vulnerability in the ReadWriteLock class, where a local attacker can craft a malicious SQLite database to cause the lock acquisition to hang or stall indefinitely. This could disrupt applications relying on filelock for synchronization.

Technologies: [filelock (PyPI)](https://junglewise.ai/threats/technologies/filelock), [Tox-Dev Filelock](https://junglewise.ai/threats/technologies/tox-dev-filelock). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi), [Tox-Dev](https://junglewise.ai/threats/vendors/tox-dev).

## Quick answers

**Is CVE-2026-112915 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-112915 being exploited in the wild.

**How severe is CVE-2026-112915?** Medium severity, with a CVSS score of 5.5, published 20 October 2026.

**Which products and versions are affected?** filelock (PyPI) >= 3.20.4, <= 4.2.0, ECOSYSTEM:introduced=3.20.4,fixed=4.2.1; Tox-Dev Filelock 3.20.4 to 4.2.1.

**Is there a fix for CVE-2026-112915?** Yes. filelock (PyPI): upgrade to 4.2.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-112915 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-112915?** Check whether you run filelock (PyPI) or Tox-Dev Filelock at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- filelock (PyPI): upgrade to 4.2.1 or later

  ```sh
  pip install "filelock>=4.2.1"
  ```


## Technical details

The ReadWriteLock implementation in filelock stores lock state in a SQLite database without bounding schema complexity or query work. An attacker with local file system access can replace the database with a crafted version containing unbounded queries or expensive schema operations. When the lock is acquired (or initially opened in versions 3.20.4, or on every acquisition in 3.30.0+), the SQLite operations hang, causing a denial of service.

## Affected products

- tox-dev filelock 3.20.4 to 4.2.1

## Identifiers

- CVE-2026-112915
- GHSA-cwqr-hh33-gh44

## Timeline

- 2026-10-20: disclosed
- 2026-10-17: patched

## References

- [https://github.com/tox-dev/filelock/commit/5e3f2ec0c5fb17cb2635b60b2b68bc63ab81ca2d](https://github.com/tox-dev/filelock/commit/5e3f2ec0c5fb17cb2635b60b2b68bc63ab81ca2d)
- [https://github.com/tox-dev/filelock/pull/834](https://github.com/tox-dev/filelock/pull/834)

## Related threats

- [filelock StrictSoftFileLock symlink race privilege escalation](https://junglewise.ai/threats/cve-2026-112938-filelock-strictsoftfilelock-follows-a-symbolic-link-swapped-in)
- [filelock: ReadWriteLock on Windows acts on SQLite side files another local user places beside its database](https://junglewise.ai/threats/cve-2026-112913-filelock-readwritelock-on-windows-acts-on-sqlite-side-files)
- [filelock WindowsFileLock mode parameter permission enforcement failure](https://junglewise.ai/threats/cve-2026-112910-filelock-windowsfilelock-ignores-mode-a-0o600-lock-file-and-the)
- [filelock StrictSoftFileLock directory permission bypass](https://junglewise.ai/threats/cve-2026-112908-filelock-strictsoftfilelock-creates-its-claim-directories)
- [filelock: On Windows an oplock on a soft lock's marker holds SoftFileLock.acquire() past its timeout and blocks the stale break](https://junglewise.ai/threats/cve-2026-112907-filelock-on-windows-an-oplock-on-a-soft-lock-s-marker-holds)