CVE-2026-125110
Description
A flaw was found in Rack. An unauthenticated remote attacker can bypass path-specific security headers by requesting files using paths containing raw or percent-encoded dot segments. This issue occurs because the static file serving component normalizes paths when locating files but evaluates header rules against unnormalized paths. Consequently, protected files can be delivered to clients without configured protections, such as Content-Security-Policy (CSP) or Content-Disposition headers.
Statement
This vulnerability is rated as Moderate severity because, although exploitable remotely without authentication, it does not allow arbitrary file retrieval or server compromise, but only bypasses path-specific HTTP response headers on already accessible static files. In standard Red Hat deployments, Rack applications are only affected if they specifically rely on Rack::Static header rules to apply security policies such as restrictive Content-Security-Policy or Content-Disposition headers. Deployments that do not configure location-dependent header directives or that manage security headers at an edge proxy are not impacted.
Mitigation
Configure an edge reverse proxy (such as Apache HTTP Server or Nginx) in front of the Rack service to normalize URI paths and reject incoming requests containing raw or percent-encoded dot segments (`..` or `%2e%2e`). Alternatively, define required security headers, such as Content-Security-Policy or Content-Disposition, directly within the reverse proxy configuration so they apply consistently regardless of application-level path routing.
Caveat: Blocking dot segments at the proxy layer may impact web applications that legitimately handle path traversal sequences in query strings. Reloading or restarting web server services to apply proxy configuration changes will temporarily interrupt active connections.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.3 | N/A | 5.3 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | Low | N/A | Low |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Understanding the Weakness (CWE)
Confidentiality,Integrity,Access Control
Technical Impact: Read Files or Directories; Modify Files or Directories; Bypass Protection Mechanism
An attacker may be able to traverse the file system to unintended locations and read or overwrite the contents of unexpected files. If the files are used for a security mechanism than an attacker may be able to bypass the mechanism.
Frequently Asked Questions
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