How severe is CVE-2026-34785?

CVE-2026-34785 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2026-34785 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (31st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-34785?

CVE-2026-34785 affects Rack. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-34785?

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-2026-34785 have an EU (EUVD) identifier?

Yes. CVE-2026-34785 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-18382.

When was CVE-2026-34785 published?

CVE-2026-34785 was published on 2026-04-02 and last updated on 2026-06-30.

CVE-2026-34785

CVE-2026-34785 is a high-severity vulnerability in Rack with a CVSS 3.x base score of 7.5. 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-187.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 0% (31st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-18382
Weakness: CWE-187
Affected product: Rack
Published: 2026-04-02
Last modified: 2026-06-30

Description

Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Static determines whether a request should be served as a static file using a simple string prefix check. When configured with URL prefixes such as "/css", it matches any request path that begins with that string, including unrelated paths such as "/css-config.env" or "/css-backup.sql". As a result, files under the static root whose names merely share the configured prefix may be served unintentionally, leading to information disclosure. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.

Frequently asked questions

What is CVE-2026-34785?: Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Static determines whether a request should be served as a static file using a simple string prefix check. When configured with URL prefixes such as "/css", it matches any request path that begins with that string, including unrelated paths such as "/css-config.env" or "/css-backup.sql". As a result, files under the static root whose names merely share the configured prefix may be served unintentionally, leading to information disclosure. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.
How severe is CVE-2026-34785?: CVE-2026-34785 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2026-34785 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (31st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-34785?: CVE-2026-34785 affects Rack. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-34785?: 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-2026-34785 have an EU (EUVD) identifier?: Yes. CVE-2026-34785 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-18382.
When was CVE-2026-34785 published?: CVE-2026-34785 was published on 2026-04-02 and last updated on 2026-06-30.

References

Affected products (1)

cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:*

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