CVE-2026-49991

HIGHPre-NVD 8.68.6—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.6 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 65% 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, secondary
Elevated
8.6EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.6Exploit: Elevated riskExposed: 0

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

RustFS is a distributed object storage system built in Rust. In 1.0.0-beta.4, authenticated users with only PutObject permission on their own bucket can exploit a path traversal vulnerability in the Snowball auto-extract feature to write arbitrary objects into other users' buckets, completely breaking multi-tenant isolation. The vulnerability chains three flaws: No ../ sanitization in tar entry key normalization; IAM wildcard matching uses raw (uncleaned) paths; and Filesystem path cleaning resolves ../ across bucket boundaries.

CVSS v3
8.6
EG Score
8.6(medium)
EG Risk
70(Attend)
EG Risk 70/100SSVC: Attend

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
Severity86% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
0%
EPSS %ILE
35%
KEV
Not listed

Published

June 26, 2026

Last Modified

June 29, 2026

Advisory Details (1)

Auto-updated Jun 26, 2026
🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available

RustFS Snowball Auto-Extract: Path Traversal allows cross-bucket object injection · Advisory · rustfs/rustfs · GitHub

https://github.com/rustfs/rustfs/security/advisories/GHSA-f4vq-9ffr-m8m3

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 6× in last 7d / 40× 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.

Showing the most recent 100 of 105 total refreshes for this CVE.

  1. 2026-09-11 14:53 UTCEPSS rescore
  2. 2026-09-10 09:35 UTCEPSS rescore
  3. 2026-09-08 22:01 UTCEPSS rescore
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  11. 2026-08-30 19:20 UTCEG score recompute
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  1. 2026-08-20 06:45 UTCEG score recompute
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  20. 2026-08-09 18:35 UTCEG score recompute
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  23. 2026-08-08 16:37 UTCEPSS rescore
  24. 2026-08-07 23:09 UTCEG score recompute
  25. 2026-08-06 14:33 UTCEG score recompute
  26. 2026-08-06 13:47 UTCEPSS rescore
  27. 2026-08-06 03:40 UTCEG score recompute
  28. 2026-08-05 19:17 UTCEPSS rescore
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  30. 2026-08-04 15:10 UTCEPSS rescore
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  37. 2026-07-30 22:14 UTCEG score recompute
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  40. 2026-07-30 01:30 UTCEPSS rescore
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  42. 2026-07-28 15:37 UTCEPSS rescore
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  44. 2026-07-27 01:31 UTCEG score recompute
  45. 2026-07-26 14:54 UTCEPSS rescore
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  47. 2026-07-25 14:18 UTCEPSS rescore
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  50. 2026-07-23 03:18 UTCEG score recompute
  51. 2026-07-22 14:08 UTCEPSS rescore
  52. 2026-07-21 15:25 UTCEPSS rescore
  53. 2026-07-20 17:08 UTCEPSS rescore
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  65. 2026-07-11 08:27 UTCEPSS rescore
  66. 2026-07-09 19:10 UTCEPSS rescore
  67. 2026-07-08 15:16 UTCEPSS rescore
  68. 2026-07-07 13:46 UTCEPSS rescore
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  72. 2026-07-01 15:07 UTCEPSS rescore
  73. 2026-06-30 23:22 UTCEPSS rescore
  74. 2026-06-29 14:06 UTCEPSS rescore
  75. 2026-06-29 14:06 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2026-49991?
CVE-2026-49991 is a high vulnerability published on June 26, 2026. RustFS is a distributed object storage system built in Rust. In 1.0.0-beta.4, authenticated users with only PutObject permission on their own bucket can exploit a path traversal vulnerability in the Snowball auto-extract feature to write arbitrary objects into other users' buckets, completely…
When was CVE-2026-49991 disclosed?
CVE-2026-49991 was first published in the National Vulnerability Database on June 26, 2026, with the most recent update on June 29, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-49991 actively exploited?
CVE-2026-49991 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 65.1% of all scored CVEs.
What is the CVSS score of CVE-2026-49991?
CVE-2026-49991 has a CVSS v3 base score of 8.6 (NVD).
How do I remediate CVE-2026-49991?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-49991, 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.

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