CVE-2026-39243

MEDIUMPre-NVD 5.55.5—
EchelonGraph scoreHIGH confidence

Score 5.5 from GitHub Security Advisory published 2026-07-10. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 5.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Elevated
5.5
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.5Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

decompress before 4.2.2 allows arbitrary hardlink creation during archive extraction, enabling file read disclosure and file corruption. When processing hardlink entries (type === 'link'), the x.linkname field from the archive is passed directly to fs.link() without validation (index.js line 113). An attacker can craft an archive with a hardlink entry whose linkname is an absolute path to any file on the same filesystem. This creates a hardlink inside the extraction directory that shares the same inode as the target file, enabling both reading and overwriting the original file's content. Hardlinks are limited to files on the same filesystem and cannot target directories.

CVSS v3
5.5
EG Score
5.5(high)
EG Risk
41(Track)
EG Risk 41/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity55% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
16.2%
KEV
Not listed

Published

July 9, 2026

Last Modified

July 13, 2026

Advisory Details (2)

Auto-updated Jul 10, 2026
🔬 Proof of concept available. No patch confirmed yet.
generic🟡 PoC Available

[CVE-2026-39243] Arbitrary hardlink creation during extraction → file read disclosure & corruption · Issue #113 · kevva/decompress · GitHub

https://github.com/kevva/decompress/issues/113
generic

GitHub - kevva/decompress: Extracting archives made easy · GitHub

https://github.com/kevva/decompress

Vendor Advisories for CVE-2026-39243(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 9× in last 7d / 28× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

  1. 2026-07-23 14:18 UTCEPSS rescore
  2. 2026-07-23 14:18 UTCEPSS rescore
  3. 2026-07-23 03:10 UTCEG score recompute
  4. 2026-07-22 14:08 UTCEPSS rescore
  5. 2026-07-21 15:24 UTCEPSS rescore
  6. 2026-07-20 17:08 UTCEPSS rescore
  7. 2026-07-19 14:31 UTCEPSS rescore
  8. 2026-07-19 02:29 UTCEPSS rescore
  9. 2026-07-18 10:04 UTCEPSS rescore
  10. 2026-07-16 17:03 UTCEPSS rescore
  11. 2026-07-16 17:01 UTCGHSA enrichment
  12. 2026-07-15 17:56 UTCGHSA enrichment
  13. 2026-07-15 16:57 UTCEPSS rescore
  14. 2026-07-15 16:57 UTCEPSS rescore
  15. 2026-07-15 02:00 UTCEPSS rescore
  16. 2026-07-14 18:52 UTCGHSA enrichment
  17. 2026-07-13 22:30 UTCEPSS rescore
  18. 2026-07-13 19:44 UTCGHSA enrichment
  19. 2026-07-13 06:13 UTCEPSS rescore
  20. 2026-07-13 06:13 UTCEPSS rescore
  21. 2026-07-12 20:40 UTCEG score recompute▲ 5.50
  22. 2026-07-12 20:40 UTCGHSA enrichment
  23. 2026-07-12 05:46 UTCEPSS rescore
  24. 2026-07-11 08:27 UTCEPSS rescore
  25. 2026-07-10 15:37 UTCMITRE cvelistV5CVSS v3 → 5.5 · severity → MEDIUM
Show 3 more
  1. 2026-07-09 23:47 UTCNVD update
  2. 2026-07-09 21:42 UTCEG score recompute
  3. 2026-07-09 21:40 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-39243?
CVE-2026-39243 is a medium vulnerability published on July 9, 2026. decompress before 4.2.2 allows arbitrary hardlink creation during archive extraction, enabling file read disclosure and file corruption. When processing hardlink entries (type === 'link'), the x.linkname field from the archive is passed directly to fs.link() without validation (index.js line 113).…
When was CVE-2026-39243 disclosed?
CVE-2026-39243 was first published in the National Vulnerability Database on July 9, 2026, with the most recent update on July 13, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-39243 actively exploited?
CVE-2026-39243 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 16.2% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-39243?
CVE-2026-39243 has a CVSS v3.1 base score of 5.5 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-39243?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-39243, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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