CVE-2026-34785
HIGHDescription
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 to fix
This Ubuntu release reached end-of-life on 2019-04-02.
This Ubuntu release reached end-of-life on 2019-04-02.
This Ubuntu release reached end-of-life on 2019-04-02.
This Ubuntu release reached end-of-life on 2019-04-02.
This Ubuntu release reached end-of-life on 2023-05-31. Extended security maintenance is available until 2028-04-01.
This Ubuntu release reached end-of-life on 2025-05-31. Extended security maintenance is available until 2030-04-02.
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Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 32% of all known CVEs.
References
Related Vulnerabilities
Other CWE-187 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2024-41110 | Critical | 9.9 | 16% | - | Fix |
| CVE-2022-31802 | Critical | 9.8 | 1.3% | - | Fix |
| CVE-2024-39742 | High | 8.1 | 0.8% | - | Fix |
| CVE-2026-35031 | Critical | 9.9 | 0.8% | - | Fix |
| CVE-2026-62750 | High | 6.5 | 0.6% | - | Fix |
| CVE-2026-14687 | Medium | 5.3 | 0.5% | - | - |
Common questions
How do I fix CVE-2026-34785?
Published advisories record a fix for 5 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2026-34785 being actively exploited?
Not that we know of. CVE-2026-34785 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.39% is the estimated probability that it will be exploited in the next 30 days. That is higher than 32% of all scored CVEs.
How severe is CVE-2026-34785?
CVE-2026-34785 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-34785 affect?
Published advisories record a fix for ruby-rack (Debian), librack-ruby (Ubuntu), librack-ruby1.8 (Ubuntu), librack-ruby1.9.1 (Ubuntu), and 1 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-24.