SB2026040258 - Multiple vulnerabilities in Rack

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Main Vulnerability Database SB2026040258

SB2026040258 - Multiple vulnerabilities in Rack

Published: April 2, 2026

Security Bulletin ID SB2026040258
Severity
Medium
Patch available
YES
Number of vulnerabilities 13
Exploitation vector Remote access
Highest impact Information disclosure

Breakdown by Severity

Medium 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 13 secuirty vulnerabilities.


1) CRLF injection (CVE-ID: CVE-2026-26962)

The vulnerability allows a remote attacker to inject arbitrary data in server response.

The vulnerability exists due to insufficient validation of attacker-supplied data within Rack::Multipart::Parser. A remote attacker can pass specially crafted data to the application containing CR-LF characters and modify application behavior.


2) Resource exhaustion (CVE-ID: CVE-2026-34230)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to application does not properly control consumption of internal resources in "Rack::Utils.select_best_encoding". A remote attacker can trigger resource exhaustion and perform a denial of service (DoS) attack.


3) Permissive Regular Expression (CVE-ID: CVE-2026-34763)

The vulnerability allows a remote attacker to gain access to sensitive information on the system.

The vulnerability exists due to unescaped regex interpolation in "Rack::Directory". A remote attacker can cause Root directory disclosure on the system.


4) Incorrect Behavior Order: Validate Before Canonicalize (CVE-ID: CVE-2026-34786)

The vulnerability allows a remote attacker to gain unauthorized access to otherwise restricted functionality.

The vulnerability exists due to incorrect behavior order when "Rack::Static#applicable_rules" evaluates several "header_rules" types. A remote attacker can request an encoded form of the path and bypass those headers.


5) Improper Handling of Length Parameter Inconsistency (CVE-ID: CVE-2026-34831)

The vulnerability allows a remote attacker to compromise the target system.

The vulnerability exists due to "Content-Length" mismatch in "Rack::Files" error responses. A remote attacker can cause response parsing inconsistencies or response desynchronization.


6) Interpretation Conflict (CVE-ID: CVE-2026-32762)

The vulnerability allows a remote attacker to compromise the target system.

The vulnerability exists due to interpretation conflict in the "Forwarded" header. A remote attacker can gain access to values for "host", "proto", "for" or related URL components


7) Resource exhaustion (CVE-ID: CVE-2026-34826)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to application does not properly control consumption of internal resources within excessive overlapping ranges. A remote attacker can trigger resource exhaustion and perform a denial of service (DoS) attack.


8) Improper Validation of Syntactic Correctness of Input (CVE-ID: CVE-2026-34835)

The vulnerability allows a remote attacker to compromise the target system.

The vulnerability exists due to the "Rack::Request" accepts invalid Host characters. A remote attacker can bypass host allowlists and poison generated links, redirects, or origin-dependent security decisions.


9) Permissive Regular Expression (CVE-ID: CVE-2026-34830)

The vulnerability allows a remote attacker to gain access to sensitive information on the system.

The vulnerability exists due to permissive regular expression in "Rack::Sendfile#map_accel_path". A remote attacker can cause nginx to serve unintended files from configured internal locations.


10) Partial String Comparison (CVE-ID: CVE-2026-34785)

The vulnerability allows a remote attacker to gain access to potentially sensitive information.

The vulnerability exists due to partial string comparison issue in "Rack::Static". A remote attacker can gain unauthorized access to sensitive information on the system.


11) Resource exhaustion (CVE-ID: CVE-2026-34829)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to application does not properly control consumption of internal resources without "Content-Length" header. A remote attacker can trigger resource exhaustion and perform a denial of service (DoS) attack.


12) Resource exhaustion (CVE-ID: CVE-2026-34827)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to application does not properly control consumption of internal resources within escape-heavy quoted parameters.. A remote attacker can trigger resource exhaustion and perform a denial of service (DoS) attack.


13) Interpretation Conflict (CVE-ID: CVE-2026-26961)

The vulnerability allows a remote attacker to compromise the target system.

The vulnerability exists due to the "Rack::Multipart::Parser" extracts the "boundary" parameter from multipart/form-data using a greedy regular expression. A remote attacker can bypass upstream filtering of uploaded files or form fields.


Remediation

Install update from vendor's website.

References