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.
CVE-2026-39243
MEDIUMPre-NVD 5.55.5—Trending — 5 sources updated this weekElevated
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
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.
- CVSS v3
- 5.5
- EG Score
- 5.5(high)
- EPSS
- 9.4%
- KEV
- Not listed
Published
July 9, 2026
Last Modified
July 10, 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/113generic
GitHub - kevva/decompress: Extracting archives made easy · GitHub
https://github.com/kevva/decompressVendor 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 8× in last 7d / 8× 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.
- 2026-07-12 20:40 UTCEG score recompute▲ 5.50
- 2026-07-12 20:40 UTCGHSA enrichment
- 2026-07-12 05:46 UTCEPSS rescore
- 2026-07-11 08:27 UTCEPSS rescore
- 2026-07-10 15:37 UTCMITRE cvelistV5CVSS v3 → 5.5 · severity → MEDIUM
- 2026-07-09 23:47 UTCNVD update
- 2026-07-09 21:42 UTCEG score recompute
- 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 10, 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 9.4% 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
Explore the affected products and dependency analysis for CVE-2026-39243
Is Your Infrastructure Affected by CVE-2026-39243?
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