Vulnerability · Published May 28, 2026 · Assigned by CPANSec
CVE-2026-9658Plack::Middleware::Security::Common versions before 0.13.1 for Perl did not block header injections in request paths
High 7.3
In plain English
A high-severity security flaw in Plack::Middleware::Security::Common from RRWO. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 13% of all known vulnerabilities).
Official description
Plack::Middleware::Security::Common versions before 0.13.1 for Perl did not block header injections in request paths. The header injection rule was ineffective at blocking header injections in the request paths unless they were double-encoded, for example, GET /path\r\nHTTP/1.1\r\nHost: secret.example.com Note that it is unclear whether request paths with CRLF followed by additional headers would be blocked by reverse proxies, or how they would be processed by Plack-based servers.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| RRWO | Plack::Middleware::Security::Common | 0 – before 0.13.1 |
Weakness: CWE-790, CWE-113 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L