CVE-2026-27607

CRITICALNVD 9.19.1
EchelonGraph scoreMEDIUM confidence

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

This critical-severity CVE scores 9.1 under NVD CVSS v3. EPSS exploit probability: 0.4% (31st percentile of EPSS-scored CVEs). GitHub Security Advisory CVSS 8.1 is lower than this score; a lower GitHub score revises it only when its advisory is newer than the CVE record's last change, and this advisory (published 2026-02-25) is not newer than that change (2026-06-17), so it does not.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3

Also known asEUVD-2026-8588 (ENISA EUVD) · GHSA-w5fh-f8xh-5x3p (GitHub Security Advisories)Source: ENISA EUVD

9.1EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 9.1Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

RustFS is a distributed object storage system built in Rust. In versions 1.0.0-alpha.56 through 1.0.0-alpha.82, RustFS does not validate policy conditions in presigned POST uploads (PostObject), allowing attackers to bypass content-length-range, starts-with, and Content-Type constraints. This enables unauthorized file uploads exceeding size limits, uploads to arbitrary object keys, and content-type spoofing, potentially leading to storage exhaustion, unauthorized data access, and security bypasses. Version 1.0.0-alpha.83 fixes the issue.

CVSS v3
9.1
EG Score
9.1CRITICALmedium confidence
EG Risk
41
EG Risk 41/100

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)
Severity91% × 45%
Impact severity (EG Severity): CVSS 9.1 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.4% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
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 none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (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
0.4%
EPSS %ILE
31st
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 (9.1): severity, escalated by confirmed exploitation. This CVE's 9.1 is its impact severity (EG Severity), not escalated.

EG Severity
9.1 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
EG Likelihood
0.4% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-11). 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; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

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 none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (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; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (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

February 25, 2026

Last Modified

June 17, 2026

Advisory Details (1)

Auto-updated Sep 16, 2026
Patch available. Sources: github.
GitHub advisoryMentions a patch (unverified)

Missing Post Policy Validation leads to Arbitrary Object Write · Advisory · rustfs/rustfs · GitHub

https://github.com/rustfs/rustfs/security/advisories/GHSA-w5fh-f8xh-5x3p

Vendor Advisories for CVE-2026-27607(1)

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

Patch Availability(1)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
rustrustfs @ 1.0.0-alpha.83 (fixes >= 1.0.0-alpha.56, < 1.0.0-alpha.82)—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)
crates.io(1)
PackageVulnerable rangeFix by version rangeDependents
rustfs—
  • 1.0.0-alpha.56 up to 1.0.0-alpha.83: fixed in 1.0.0-alpha.83
—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 13× 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 its CVE.org record (CNA or CISA ADP). 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). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 157 rows on record for this CVE, as 98 entries (2 repeats merged).

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. 2 repeat rows among the latest 100 are merged into the row they repeat. The 57 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-12 16:33 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  2. 2026-11-12 16:32 UTCEchelonGraph re-scored
  3. 2026-11-12 16:32 UTCGHSA enrichmentGHSA-w5fh-f8xh-5x3p · GitHub severity HIGH · GitHub CVSS 8.1
  4. 2026-11-11 16:39 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  5. 2026-11-11 15:24 UTCEchelonGraph re-scored
  6. 2026-11-11 15:24 UTCGHSA enrichmentGHSA-w5fh-f8xh-5x3p · GitHub severity HIGH · GitHub CVSS 8.1
  7. 2026-11-10 16:43 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  8. 2026-11-10 14:19 UTCEchelonGraph re-scored
  9. 2026-11-10 14:19 UTCGHSA enrichmentGHSA-w5fh-f8xh-5x3p · GitHub severity HIGH · GitHub CVSS 8.1
  10. 2026-11-09 16:34 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  11. 2026-11-09 13:14 UTCEchelonGraph re-scored
  12. 2026-11-09 13:14 UTCGHSA enrichmentGHSA-w5fh-f8xh-5x3p · GitHub severity HIGH · GitHub CVSS 8.1
  13. 2026-11-08 16:38 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  14. 2026-11-08 12:09 UTCEchelonGraph re-scored
  15. 2026-11-08 12:09 UTCGHSA enrichmentGHSA-w5fh-f8xh-5x3p · GitHub severity HIGH · GitHub CVSS 8.1
  16. 2026-11-07 16:38 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  17. 2026-11-07 11:00 UTCEchelonGraph re-scored
  18. 2026-11-07 11:00 UTCGHSA enrichmentGHSA-w5fh-f8xh-5x3p · GitHub severity HIGH · GitHub CVSS 8.1
  19. 2026-11-06 16:37 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  20. 2026-11-06 09:56 UTCEchelonGraph re-scored
  21. 2026-11-06 09:56 UTCGHSA enrichmentGHSA-w5fh-f8xh-5x3p · GitHub severity HIGH · GitHub CVSS 8.1
  22. 2026-11-06 04:25 UTCOSV refresh
  23. 2026-11-05 08:52 UTCEchelonGraph re-scored
  24. 2026-11-05 08:52 UTCGHSA enrichmentGHSA-w5fh-f8xh-5x3p · GitHub severity HIGH · GitHub CVSS 8.1
  25. 2026-11-04 16:35 UTCEPSS rescoreEPSS 0.4% · 30th percentile
Show 73 more
  1. 2026-11-04 07:47 UTCEchelonGraph re-scored
  2. 2026-11-04 07:47 UTCGHSA enrichmentGHSA-w5fh-f8xh-5x3p · GitHub severity HIGH · GitHub CVSS 8.1
  3. 2026-11-03 16:47 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  4. 2026-11-03 06:42 UTCEchelonGraph re-scored
  5. 2026-11-03 06:42 UTCGHSA enrichmentGHSA-w5fh-f8xh-5x3p · GitHub severity HIGH · GitHub CVSS 8.1
  6. 2026-11-02 16:44 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  7. 2026-11-02 05:38 UTCEchelonGraph re-scored
  8. 2026-11-02 05:38 UTCGHSA enrichmentGHSA-w5fh-f8xh-5x3p · GitHub severity HIGH · GitHub CVSS 8.1
  9. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  10. 2026-11-01 07:56 UTCEchelonGraph re-scored
  11. 2026-11-01 07:56 UTCGHSA enrichmentGHSA-w5fh-f8xh-5x3p · GitHub severity HIGH · GitHub CVSS 8.1
  12. 2026-11-01 04:33 UTCEchelonGraph re-scored
  13. 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  14. 2026-10-31 03:29 UTCEchelonGraph re-scored
  15. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  16. 2026-10-30 02:23 UTCEchelonGraph re-scored
  17. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  18. 2026-10-29 01:19 UTCEchelonGraph re-scored
  19. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  20. 2026-10-28 00:13 UTCEchelonGraph re-scored
  21. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  22. 2026-10-26 23:06 UTCEchelonGraph re-scored
  23. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  24. 2026-10-25 18:38 UTCEchelonGraph re-scored
  25. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  26. 2026-10-25 14:38 UTCEchelonGraph re-scored
  27. 2026-10-24 17:31 UTCEchelonGraph re-scored
  28. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  29. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  30. 2026-10-23 16:27 UTCEchelonGraph re-scored
  31. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  32. 2026-10-22 15:21 UTCEchelonGraph re-scored
  33. 2026-10-21 16:32 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  34. 2026-10-21 14:14 UTCEchelonGraph re-scored
  35. 2026-10-20 16:32 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  36. 2026-10-20 13:05 UTCEchelonGraph re-scored
  37. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  38. 2026-10-19 11:59 UTCEchelonGraph re-scored
  39. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  40. 2026-10-18 03:51 UTCEchelonGraph re-scored
  41. 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  42. 2026-10-17 08:58 UTCEchelonGraph re-scored
  43. 2026-10-16 16:41 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  44. 2026-10-16 07:51 UTCEchelonGraph re-scored
  45. 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  46. 2026-10-15 06:46 UTCEchelonGraph re-scored
  47. 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  48. 2026-10-14 02:30 UTCEchelonGraph re-scored
  49. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
  50. 2026-10-12 22:45 UTCEchelonGraph re-scored
  51. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  52. 2026-10-12 16:17 UTCEchelonGraph re-scored
  53. 2026-10-11 19:59 UTCEchelonGraph re-scored
  54. 2026-10-11 17:13 UTCEchelonGraph re-scored
  55. 2026-10-11 14:44 UTCEchelonGraph re-scored
  56. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  57. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  58. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  59. 2026-10-09 13:58 UTCOSV refresh
  60. 2026-10-08 17:11 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  61. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  62. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  63. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  64. 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  65. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  66. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  67. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  68. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  69. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  70. 2026-09-26 00:26 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  71. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  72. 2026-09-19 21:30 UTCOSV refresh
  73. 2026-09-18 19:27 UTCEPSS rescoreEPSS 0.3% · 25th percentile

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Frequently asked(5)

What is CVE-2026-27607?
CVE-2026-27607 is a critical-severity vulnerability; its CVE record was published on February 25, 2026. RustFS is a distributed object storage system built in Rust. In versions 1.0.0-alpha.56 through 1.0.0-alpha.82, RustFS does not validate policy conditions in presigned POST uploads (PostObject), allowing attackers to bypass content-length-range, starts-with, and Content-Type constraints. This…
When was the CVE record for CVE-2026-27607 published?
The CVE record for CVE-2026-27607 was published on February 25, 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 17, 2026; the record at its source may have been updated since.
Is CVE-2026-27607 actively exploited?
CVE-2026-27607 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (31st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-27607?
CVE-2026-27607 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2026-27607?
A fix for CVE-2026-27607 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-27607 are linked in the Vendor Advisories panel on this page.

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