Improper Validation of Syntactic Correctness of Input in Rack - CVE-2026-34835
Published: April 2, 2026
Vulnerability identifier: #VU124830
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-34835
CWE-ID: CWE-1286
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Rack
Affected software:
Rack
Rack
Detailed vulnerability description
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.
How to mitigate CVE-2026-34835
Install updates from vendor's website.