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filelock: SoftFileLock stale-lock break removes a live lock file on a reused inode number and admits two holders

Type: advisorySource: Official CVE List1 source record

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.

Announced Source revision 1
Original source ↗

CVE-2026-112935

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-112935

filelock

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "vendor": "tox-dev",
    "product": "filelock",
    "versions": [
      {
        "status": "affected",
        "version": ">= 3.22.0, < 4.2.1"
      }
    ]
  }
]
Related CVEs
CVE-2026-112935

Source reference: /cveMetadata/cveId

Publisher severity

medium

Source reference: /containers/cna/metrics

Event
#42203 · Revision 1
Added to Heist Feed
Publisher date
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