CVE-2026-42091

MEDIUMNVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.5 under NVD CVSS v3. EPSS exploit probability: 0.0%, top 96% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Elevated
6.5
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 6.5Exploit: NoneExposed: 0

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

goshs is a SimpleHTTPServer written in Go. Prior to version 2.0.2, the PUT upload handler (httpserver/updown.go) lacks the CSRF token validation that was added to the POST upload handler during the CVE-2026-40883 fix. Combined with the unconditional Access-Control-Allow-Origin: * on the OPTIONS preflight handler (httpserver/server.go), any website can write arbitrary files to a goshs instance through the victim's browser — bypassing network isolation (e.g. localhost, internal network). This issue has been patched in version 2.0.2.

CVSS v3
6.5
EG Score
6.5(medium)
EPSS
6.0%
KEV
Not listed

Published

May 4, 2026

Last Modified

May 12, 2026

Advisory Details (3)

Auto-updated May 4, 2026
🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available

Cross-Origin Arbitrary File Write via Missing CSRF on PUT and Wildcard CORS · Advisory · patrickhener/goshs · GitHub

https://github.com/patrickhener/goshs/security/advisories/GHSA-rhf7-wvw3-vjvm
generic

Release v2.0.2 · patrickhener/goshs · GitHub

https://github.com/patrickhener/goshs/releases/tag/v2.0.2
generic

Fix security issue https://github.com/patrickhener/goshs/security/adv… · patrickhener/goshs@0e715b9 · GitHub

https://github.com/patrickhener/goshs/commit/0e715b94e10c3d1aa552276000f15f104dee2f32

Affected Packages

(2 across 1 ecosystem)
Go(2)
PackageVulnerable rangeFixed inDependents
github.com/patrickhener/goshs———
github.com/patrickhener/goshs/v2—2.0.2—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 32× 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. 2026-07-15 16:57 UTCEPSS rescore
  2. 2026-07-15 02:00 UTCEPSS rescore
  3. 2026-07-13 06:13 UTCEPSS rescore
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  9. 2026-07-07 13:46 UTCEPSS rescore
  10. 2026-07-06 16:27 UTCEPSS rescore
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  12. 2026-07-05 02:30 UTCEPSS rescore
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  14. 2026-07-01 15:06 UTCEPSS rescore
  15. 2026-06-30 23:22 UTCEPSS rescore
  16. 2026-06-29 14:06 UTCEPSS rescore
  17. 2026-06-28 14:07 UTCEPSS rescore
  18. 2026-06-28 04:56 UTCEPSS rescore
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  20. 2026-06-25 13:49 UTCEPSS rescore
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  23. 2026-06-23 21:33 UTCEPSS rescore
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  1. 2026-06-21 14:56 UTCEPSS rescore
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  3. 2026-06-21 01:59 UTCEPSS rescore
  4. 2026-06-19 19:25 UTCEPSS rescore
  5. 2026-06-18 17:52 UTCEPSS rescore
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  7. 2026-06-17 17:53 UTCEPSS rescore
  8. 2026-06-15 17:49 UTCEPSS rescore
  9. 2026-06-15 06:28 UTCEG score recompute
  10. 2026-06-14 08:07 UTCEG score recompute
  11. 2026-06-13 23:00 UTCEPSS rescore
  12. 2026-06-12 23:12 UTCEPSS rescore
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  14. 2026-06-11 19:55 UTCEG score recompute
  15. 2026-06-11 14:00 UTCEPSS rescore
  16. 2026-06-10 22:18 UTCEPSS rescore
  17. 2026-06-10 21:34 UTCEG score recompute
  18. 2026-06-10 13:22 UTCEPSS rescore
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  20. 2026-06-09 23:13 UTCEG score recompute
  21. 2026-06-08 22:37 UTCEG score recompute
  22. 2026-06-08 14:17 UTCEPSS rescore
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  24. 2026-06-07 23:06 UTCEG score recompute
  25. 2026-06-07 15:25 UTCEPSS rescore
  26. 2026-06-07 15:25 UTCEPSS rescore
  27. 2026-06-07 00:45 UTCEG score recompute
  28. 2026-06-06 02:23 UTCEG score recompute
  29. 2026-06-05 22:47 UTCEPSS rescore
  30. 2026-06-05 06:10 UTCEPSS rescore
  31. 2026-06-05 06:10 UTCEPSS rescore
  32. 2026-06-05 03:37 UTCEG score recompute
  33. 2026-06-04 13:12 UTCEPSS rescore
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  35. 2026-06-04 05:16 UTCEG score recompute
  36. 2026-06-03 06:55 UTCEG score recompute
  37. 2026-06-02 20:13 UTCEPSS rescore
  38. 2026-06-02 08:22 UTCEG score recompute
  39. 2026-06-01 13:52 UTCEPSS rescore
  40. 2026-06-01 13:52 UTCEPSS rescore
  41. 2026-06-01 10:00 UTCEG score recompute
  42. 2026-05-31 22:30 UTCEPSS rescore
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  44. 2026-05-31 00:16 UTCEPSS rescore
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  47. 2026-05-29 13:44 UTCEPSS rescore
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  49. 2026-05-28 13:44 UTCEPSS rescore
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  52. 2026-05-27 13:40 UTCEPSS rescore
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  55. 2026-05-26 13:44 UTCEPSS rescore
  56. 2026-05-26 07:18 UTCEPSS rescore
  57. 2026-05-26 07:18 UTCEPSS rescore
  58. 2026-05-23 00:08 UTCEG score recompute
  59. 2026-05-20 22:38 UTCEPSS rescore
  60. 2026-05-20 22:38 UTCEPSS rescore
  61. 2026-05-20 14:34 UTCEG score recompute
  62. 2026-05-20 11:22 UTCEPSS rescore
  63. 2026-05-20 11:22 UTCEPSS rescore

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-42091?
CVE-2026-42091 is a medium vulnerability published on May 4, 2026. goshs is a SimpleHTTPServer written in Go. Prior to version 2.0.2, the PUT upload handler (httpserver/updown.go) lacks the CSRF token validation that was added to the POST upload handler during the CVE-2026-40883 fix. Combined with the unconditional Access-Control-Allow-Origin: * on the OPTIONS…
When was CVE-2026-42091 disclosed?
CVE-2026-42091 was first published in the National Vulnerability Database on May 4, 2026, with the most recent update on May 12, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-42091 actively exploited?
CVE-2026-42091 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 6.0% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-42091?
CVE-2026-42091 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2026-42091?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-42091, 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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