CVE-2026-49991

HIGHPre-NVD 8.68.6
EchelonGraph scoreMEDIUM confidence

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

This high-severity CVE scores 8.6 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4% (35th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
Elevated

Also known asEUVD-2026-39865 (ENISA EUVD)Source: ENISA EUVD

8.6EG
EchelonGraph verdictPlan mitigationRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (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: 0.4%CVSS: 8.6Exploit: No code on recordExposed services: Not assessed

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

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
8.6HIGHmedium confidence
EG Risk
70
EG Risk 70/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity86% × 45%
Impact severity (EG Severity): CVSS 8.6 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation public PoC (CISA Vulnrichment) · Automatable yes (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: No fix is confirmed yet. Restrict network exposure of the affected system within your standard update timelines at low or medium mission impact and sooner than that at high, and watch for a fix.
EPSS PROB
0.4%
EPSS %ILE
35th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (8.6): severity, escalated by confirmed exploitation. This CVE's 8.6 is its impact severity (EG Severity), not escalated.

EG Severity
8.6 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
EG Likelihood
0.4% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-24). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

No fix is confirmed yet. Restrict network exposure of the affected system within your standard update timelines at low or medium mission impact and sooner than that at high, and watch for a fix.

Exploitation public PoC (CISA Vulnrichment) · Automatable yes (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)14 days if the affected system is publicly exposed; 60 days if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable yes (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

June 26, 2026

Last Modified

June 29, 2026

Advisory Details (1)

Auto-updated Jun 26, 2026
No fix on record yet. Sources: github.
GitHub advisoryMentions a patch (unverified)

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 9× in last 7d / 37× 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 100 of 155 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. None are among the latest 100 rows. The 55 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  2. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  3. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  4. 2026-10-25 14:22 UTCEG score recompute
  5. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  6. 2026-10-23 23:55 UTCEG score recompute
  7. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.4% · 34th percentile
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  16. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.4% · 34th percentile
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  19. 2026-10-13 20:54 UTCOSV refresh
  20. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  21. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
  22. 2026-10-12 15:59 UTCEG score recompute
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  1. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
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  8. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
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  10. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
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  12. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
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  16. 2026-09-23 17:53 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  17. 2026-09-23 07:50 UTCEG score recompute
  18. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.4% · 35th percentile
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  24. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.4% · 34th percentile
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  26. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  27. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.4% · 34th percentile
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  31. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.4% · 34th percentile
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  40. 2026-08-27 23:01 UTCEG score recompute
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  44. 2026-08-24 21:48 UTCEG score recompute
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  75. 2026-08-06 14:33 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-49991?
CVE-2026-49991 is a high-severity vulnerability; its CVE record was 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 the CVE record for CVE-2026-49991 published?
The CVE record for CVE-2026-49991 was published on June 26, 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 June 29, 2026; the record at its source may have been updated since.
Is CVE-2026-49991 actively exploited?
CVE-2026-49991 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (35th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-49991?
CVE-2026-49991 has a CVSS base score of 8.6 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-49991?
No fix for CVE-2026-49991 is confirmed yet. Until one is published, restrict network exposure of the affected system — for example, keep it off the internet or limit it to trusted networks — and watch for a fix.

Dependency Blast Radius

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