How severe is CVE-2026-27607?

CVE-2026-27607 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability high.

Is CVE-2026-27607 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (19th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-27607?

CVE-2026-27607 primarily affects Rustfs. In total, 27 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-27607?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-27607 have an EU (EUVD) identifier?

Yes. CVE-2026-27607 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-8588.

When was CVE-2026-27607 published?

CVE-2026-27607 was published on 2026-02-25 and last updated on 2026-06-17.

CVE-2026-27607

CVE-2026-27607 is a high-severity vulnerability in Rustfs with a CVSS 3.x base score of 8.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-863.

Key facts

Severity: High (CVSS 3.x base score 8.1)
EPSS exploit prediction: 0% (19th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-8588
Weakness: CWE-863
Affected product: Rustfs
Published: 2026-02-25
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2026-27607?: 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.
How severe is CVE-2026-27607?: CVE-2026-27607 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability high.
Is CVE-2026-27607 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (19th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-27607?: CVE-2026-27607 primarily affects Rustfs. In total, 27 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-27607?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-27607 have an EU (EUVD) identifier?: Yes. CVE-2026-27607 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-8588.
When was CVE-2026-27607 published?: CVE-2026-27607 was published on 2026-02-25 and last updated on 2026-06-17.

References

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

Affected products (27)

cpe:2.3:a:rustfs:rustfs:1.0.0:alpha56:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha57:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha58:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha59:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha60:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha61:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha62:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha63:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha64:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha65:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha66:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha67:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha68:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha69:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha70:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha71:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha72:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha73:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha74:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha75:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha76:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha77:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha78:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha79:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha80:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha81:*:*:*:rust:*:*
cpe:2.3:a:rustfs:rustfs:1.0.0:alpha82:*:*:*:rust:*:*

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