CVE-2026-22701 | filelock Time-of-Check-Time-of-Use (TOCTOU) Symlink Vulnerability in SoftFileLock

filelock is a platform-independent file lock for Python. Prior to version 3.20.3, a TOCTOU race condition vulnerability exists in the SoftFileLock implementation of the filelock package. An attacker with local filesystem access and permission to create symlinks can exploit a race condition between the permission validation and file creation to cause lock operations to fail or behave unexpectedly. The vulnerability occurs in the _acquire() method between raise_on_not_writable_file() (permission check) and os.open() (file creation). During this race window, an attacker can create a symlink at the lock file path, potentially causing the lock to operate on an unintended target file or leading to denial of service. This issue has been patched in version 3.20.3.

Published: 2026-01-10 Last update: 2026-03-05 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-22701 is rated Low Risk (21.8/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.01%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-22701

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-01-10 — 0.01% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-22701

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.3 3.1 MEDIUM
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.0 4.2 [email protected]

Weakness enumeration for CVE-2026-22701

GitHub Security Advisory for CVE-2026-22701

GHSA-qmgc-5h2g-mvrw · Severity: medium · Ecosystem: pip — filelock Time-of-Check-Time-of-Use (TOCTOU) Symlink Vulnerability in SoftFileLock

OS Trackers for CVE-2026-22701

vendor priority summary link
alpine — CVE-2026-22701: 1 source package rows (py3-filelock); 6 state rows across 3 repos (3.23-main, edge-community, edge-main); fixed 0, open 6. https://security.alpinelinux.org/vuln/CVE-2026-22701
debian not yet assigned CVE-2026-22701 not yet assigned priority: Debian including 1 source packages (python-filelock), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 3, resolved 2. https://security-tracker.debian.org/tracker/CVE-2026-22701
redhat medium — https://access.redhat.com/security/cve/CVE-2026-22701
suse medium CVE-2026-22701 severity moderate: SUSE including 21 source package names (2.1.3-5.8:e2fsprogs-1.47.0-3.1, 2.1.3-5.8:libcom_err2-1.47.0-3.1, …), 72 product×package rows across 43 product lines (Container suse/multi-linux-manager/5.1/x86_64/server, Container suse/sl-micro/6.0/baremetal-os-container, … (43 product lines)): Fixed 71, First Fixed 1. https://www.suse.com/security/cve/CVE-2026-22701/
ubuntu medium CVE-2026-22701 medium priority: Ubuntu including 1 source packages (python-filelock), 7 status rows across 7 suites (bionic, focal, jammy, noble, plucky, questing, upstream): released 4, ignored 1, needed 1, needs-triage 1. https://ubuntu.com/security/CVE-2026-22701

Affected software / configurations for CVE-2026-22701

Vendor Product Version Raw CPE
tox-dev filelock < 3.20.3 cpe:2.3:a:tox-dev:filelock:*:*:*:*:*:python:*:*

References for CVE-2026-22701

cvelogic Threat Intelligence