CVE-2026-34785Network attack vector

Unauthenticated file disclosure via prefix-only route matching

Published Apr 2, 2026 · Updated Apr 2, 2026

Information disclosure in Rack::Static before 2.2.23, 3.0.0.beta1 through 3.1.20, and 3.2.0 through 3.2.5 allows remote attackers to read files. Rack::Static#route_file uses a simple string-prefix comparison and omits the path-segment boundary before forwarding a matching request to the file server. Exposure requires Rack::Static with a configured URL prefix and a sibling file under the static root whose name starts with that prefix; only that file content is disclosed.

CVSS severity7.5
High
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Rack::Static before 2.2.23, 3.0.0.beta1 through 3.1.20, and 3.2.0 through 3.2.5 allows remote attackers to read files. Rack::Static#route_file uses a simple string-prefix comparison and omits the path-segment boundary before forwarding a matching request to the file server. Exposure requires Rack::Static with a configured URL prefix and a sibling file under the static root whose name starts with that prefix; only that file content is disclosed.

The record

CVE
CVE-2026-34785
Published
Apr 2, 2026
Updated
Apr 2, 2026
Vendor
Rack
Product
Rack
Classifications
CWE-200, CWE-187, CWE-552, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 2, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 2, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2.2.23
  2. Affected versionversion=>= 3.0.0.beta1, < 3.1.21
  3. Affected versionversion=>= 3.2.0, < 3.2.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Rack · Rackversion=< 2.2.23; version=>= 3.0.0.beta1, < 3.1.21; version=>= 3.2.0, < 3.2.6

Published CVSS scores

7.5redhat-SADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
7.5SUSECVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
8.7SUSECVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
7.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-200Exposure of Sensitive Information to an Unauthorized Actor
CWE-187Partial String Comparison
CWE-552Files or Directories Accessible to External Parties
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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