CVE-2026-39243

MEDIUMPre-NVD 5.55.5
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

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 (Vulnrichment) CVSS v3.1, EPSS, GitHub Security Advisory
Elevated
5.5EG
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: 0.3%CVSS: 5.5Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

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
5.5MEDIUMmedium confidence
EG Risk
41
EG Risk 41/100

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 (value × EchelonGraph’s weight)
Severity55% × 45%
The EG Score, 5.5 of 10.
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
0.3%
EPSS %ILE
21st
KEV
Not listed

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.

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

July 9, 2026

Last Modified

July 13, 2026

Advisory Details (2)

Auto-updated Jul 10, 2026
Patch available.
Web page

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

https://github.com/kevva/decompress/issues/113
Web page

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

https://github.com/kevva/decompress

Vendor Advisories for CVE-2026-39243(2)

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

Patch Availability(2)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatdotnet8-0-main-8.0.128-1.1.hum12026-07-10redhat
npmdecompress—ghsa

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
npm(1)
PackageVulnerable rangeFix by version rangeDependents
decompress—
  • every version through 4.2.1: no fix on record
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 11× in last 7d / 42× 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.

Showing the most recent 99 of 229 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 1 repeat row among the latest 100 is merged into the row it repeats. The 130 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  2. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  3. 2026-10-12 16:10 UTCEG score recompute
  4. 2026-10-11 19:52 UTCEG score recompute
  5. 2026-10-11 17:06 UTCEG score recompute
  6. 2026-10-11 14:32 UTCEG score recompute
  7. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  8. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  9. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  10. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  11. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  12. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  13. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  14. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  15. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  16. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  17. 2026-10-01 16:07 UTCEG score recompute
  18. 2026-10-01 16:07 UTCVendor advisory
  19. 2026-10-01 16:07 UTCGHSA enrichmentGHSA-jwp9-9v96-94mx · GitHub CVSS 5.5
  20. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  21. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  22. 2026-09-28 11:09 UTCEG score recompute
  23. 2026-09-28 11:09 UTCVendor advisory
  24. 2026-09-28 11:09 UTCGHSA enrichmentGHSA-jwp9-9v96-94mx · GitHub CVSS 5.5
  25. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.3% · 20th percentile
Show 74 more
  1. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  2. 2026-09-26 00:26 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  3. 2026-09-24 11:43 UTCEG score recompute
  4. 2026-09-24 11:43 UTCVendor advisory
  5. 2026-09-24 11:43 UTCGHSA enrichmentGHSA-jwp9-9v96-94mx · GitHub CVSS 5.5
  6. 2026-09-23 06:02 UTCEG score recompute
  7. 2026-09-23 06:02 UTCVendor advisory
  8. 2026-09-23 06:02 UTCGHSA enrichmentGHSA-jwp9-9v96-94mx · GitHub CVSS 5.5
  9. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  10. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  11. 2026-09-18 05:39 UTCEG score recompute
  12. 2026-09-18 05:39 UTCVendor advisory
  13. 2026-09-18 05:39 UTCGHSA enrichmentGHSA-jwp9-9v96-94mx · GitHub CVSS 5.5
  14. 2026-09-17 19:30 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  15. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  16. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  17. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  18. 2026-09-14 07:25 UTCEG score recompute
  19. 2026-09-14 07:25 UTCVendor advisory
  20. 2026-09-14 07:25 UTCGHSA enrichmentGHSA-jwp9-9v96-94mx · GitHub CVSS 5.5
  21. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  22. 2026-09-13 08:22 UTCEG score recompute
  23. 2026-09-13 08:22 UTCVendor advisory
  24. 2026-09-13 08:22 UTCGHSA enrichmentGHSA-jwp9-9v96-94mx · GitHub CVSS 5.5
  25. 2026-09-12 15:01 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  26. 2026-09-12 03:28 UTCEG score recompute
  27. 2026-09-12 03:28 UTCVendor advisory
  28. 2026-09-12 03:28 UTCGHSA enrichmentGHSA-jwp9-9v96-94mx · GitHub CVSS 5.5
  29. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  30. 2026-09-11 09:37 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  31. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  32. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  33. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  34. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  35. 2026-09-05 22:38 UTCEG score recompute
  36. 2026-09-05 22:38 UTCVendor advisory
  37. 2026-09-05 22:38 UTCGHSA enrichmentGHSA-jwp9-9v96-94mx · GitHub CVSS 5.5
  38. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  39. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  40. 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  41. 2026-09-01 04:39 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  42. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  43. 2026-08-30 06:59 UTCEG score recompute
  44. 2026-08-30 06:59 UTCVendor advisory
  45. 2026-08-30 06:59 UTCGHSA enrichmentGHSA-jwp9-9v96-94mx · GitHub CVSS 5.5
  46. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  47. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  48. 2026-08-28 02:43 UTCEG score recompute
  49. 2026-08-28 02:43 UTCVendor advisory
  50. 2026-08-28 02:43 UTCGHSA enrichmentGHSA-jwp9-9v96-94mx · GitHub CVSS 5.5
  51. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  52. 2026-08-27 03:11 UTCEG score recompute
  53. 2026-08-27 03:11 UTCVendor advisory
  54. 2026-08-27 03:11 UTCGHSA enrichmentGHSA-jwp9-9v96-94mx · GitHub CVSS 5.5
  55. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  56. 2026-08-26 04:03 UTCEG score recompute
  57. 2026-08-26 04:03 UTCVendor advisory
  58. 2026-08-26 04:02 UTCGHSA enrichmentGHSA-jwp9-9v96-94mx · GitHub CVSS 5.5
  59. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  60. 2026-08-24 21:44 UTCEG score recompute
  61. 2026-08-24 21:44 UTCVendor advisory
  62. 2026-08-24 21:44 UTCGHSA enrichmentGHSA-jwp9-9v96-94mx · GitHub CVSS 5.5
  63. 2026-08-23 22:19 UTCEG score recompute
  64. 2026-08-23 22:19 UTCVendor advisory
  65. 2026-08-23 22:19 UTCGHSA enrichmentGHSA-jwp9-9v96-94mx · GitHub CVSS 5.5
  66. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  67. 2026-08-22 23:06 UTCVendor advisory
  68. 2026-08-22 23:06 UTCGHSA enrichmentGHSA-jwp9-9v96-94mx · GitHub CVSS 5.5
  69. 2026-08-22 00:02 UTCEG score recompute
  70. 2026-08-22 00:02 UTCVendor advisory
  71. 2026-08-22 00:02 UTCGHSA enrichmentGHSA-jwp9-9v96-94mx · GitHub CVSS 5.5
  72. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  73. 2026-08-21 00:58 UTCEG score recompute
  74. 2026-08-21 00:58 UTCVendor advisory

Related CVEs(same product + same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-39243?
CVE-2026-39243 is a medium-severity vulnerability; its CVE record was 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 the CVE record for CVE-2026-39243 published?
The CVE record for CVE-2026-39243 was published on July 9, 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 July 13, 2026; the record at its source may have been updated since.
Is CVE-2026-39243 actively exploited?
CVE-2026-39243 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (21st percentile of EPSS-scored CVEs).
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?
A fix for CVE-2026-39243 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-39243 are linked in the Vendor Advisories panel on this page.

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