filelock is a platform-independent file lock for Python. Prior to 4.2.1, UnixFileLock can truncate a regular file renamed onto the lock path when another local user has actual rename permission, or hard-linked there under a permissive hard-link policy; when an explicit mode is requested, affected versions from 3.10.2 can also change that file's mode. This issue is fixed in version 4.2.1.
CVE-2026-112909
MEDIUMPre-NVD 6.16.1ElevatedEG-KEV Tier 3: ElevatedEG-KEV is EchelonGraph's own tiering of exploitation signals from CISA KEV, CISA's SSVC data (Vulnrichment), ransomware data, public exploit-code references and EPSS.Tier 3 is not evidence of exploitation. It means public exploit code is referenced, or CISA's SSVC data says "public PoC", or EPSS ranks the CVE in the top 5%.Signals for this CVE: CISA's SSVC exploitation value: public PoC.EchelonGraph confidence 38%: a heuristic from the tier and the number of signals, not a measured probability.
EchelonGraph scoreMEDIUM confidence
“—” beside the score: it is equal to the CVSS score beside it.
This medium-severity CVE scores 6.1 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2% (12th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.
Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
Also known asEUVD-2026-105017 (ENISA EUVD) · GHSA-69hj-f68j-2879 (GitHub Security Advisories)Source: ENISA EUVD
6.1EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
- CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 6.1Exploit: No code on recordExposed services: Not assessed
A fix is available — apply it.
- CVSS v3
- 6.1
- EG Score
- 6.1MEDIUMmedium confidence
- EG Risk
- 43EG Risk 43/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity61% × 45%Impact severity (EG Severity): CVSS 6.1 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation40% × 40%EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.Automatability0% × 15%CISA's SSVC Automatable value: no (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: A fix is available. Apply it within your standard update timelines. - EPSS PROB
- 0.2%
- EPSS %ILE
- 12th
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (6.1): severity, escalated by confirmed exploitation. This CVE's 6.1 is its impact severity (EG Severity), not escalated.
- EG Severity
- 6.1 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
- EG Likelihood
- 0.2% within 30 daysSource: FIRST EPSS. FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines.
Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
October 20, 2026
Last Modified
October 27, 2026
Advisory Details (4)
Auto-updated Oct 20, 2026🔬 Proof of concept available. Patch available. Sources: github, github_pr, github_commit, github_release.
GitHub release Patch Available
4.2.1
Patch available: tox-dev/filelock 4.2.1
https://github.com/tox-dev/filelock/releases/tag/4.2.1GitHub commit Patch Available
commit e1e825b1992f (tox-dev/filelock)
Patch available: tox-dev/filelock 4.2.1 (contains commit e1e825b1992f)
https://github.com/tox-dev/filelock/commit/e1e825b1992f69fb6b346dc395d5ae4893536c0aGitHub pull request Patch Available
🐛 fix(open): keep lock files intact, honor deadlines and mode
Patch available: tox-dev/filelock 4.2.1 (PR #835 merged 2026-10-17)
https://github.com/tox-dev/filelock/pull/835GitHub advisoryMentions a patch (unverified)🟡 PoC Available
UnixFileLock truncates and chmods any regular file another user renames or hard-links onto the lock path · Advisory · tox-dev/filelock · GitHub
https://github.com/tox-dev/filelock/security/advisories/GHSA-69hj-f68j-2879Vendor Advisories for CVE-2026-112909(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(1 across 1 ecosystem)
PyPI(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| filelock | 0.2.0 ... 4.2.0 (134 versions) |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 8× in last 7d / 19× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
- 2026-11-01 16:33 UTCEPSS rescoreEPSS 0.2% · 12th percentile
- 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.2% · 12th percentile
- 2026-10-30 16:33 UTCEPSS rescoreEPSS 0.2% · 12th percentile
- 2026-10-29 16:32 UTCEPSS rescoreEPSS 0.2% · 12th percentile
- 2026-10-28 16:31 UTCEPSS rescoreEPSS 0.2% · 12th percentile
- 2026-10-27 21:06 UTCEG score recompute
- 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-26 16:30 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-25 14:51 UTCEG score recompute
- 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.1% · 1st percentile
- 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.1% · 1st percentile
- 2026-10-22 22:26 UTCEG score recompute
- 2026-10-22 21:36 UTCEG score recompute
- 2026-10-22 16:33 UTCEPSS rescoreEPSS 0.1% · 1st percentile
- 2026-10-21 16:32 UTCEPSS rescoreEPSS 0.1% · 1st percentile
- 2026-10-20 15:27 UTCEG score recompute
- 2026-10-20 14:23 UTCEG score recomputeFirst assessed: 6.1 MEDIUM
- 2026-10-20 14:21 UTCMITRE cvelistV5first tracked
Related CVEs(same product + same CWE)
Same product
10 shownPyPI:filelock
Frequently asked(5)
What is CVE-2026-112909?
CVE-2026-112909 is a medium-severity vulnerability; its CVE record was published on October 20, 2026. filelock is a platform-independent file lock for Python. Prior to 4.2.1, UnixFileLock can truncate a regular file renamed onto the lock path when another local user has actual rename permission, or hard-linked there under a permissive hard-link policy; when an explicit mode is requested, affected…
When was the CVE record for CVE-2026-112909 published?
The CVE record for CVE-2026-112909 was published on October 20, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 27, 2026; the record at its source may have been updated since.
Is CVE-2026-112909 actively exploited?
CVE-2026-112909 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (12th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-112909?
CVE-2026-112909 has a CVSS base score of 6.1 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-112909?
A fix for CVE-2026-112909 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-112909 are linked in the Vendor Advisories panel on this page.
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-112909
Is Your Infrastructure Affected by CVE-2026-112909?
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