CVE-2026-9658

Summary

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 Software

Weaknesses

• CWE-790: CWE-790 Improper Filtering of Special Elements
• CWE-113: CWE-113 Improper Neutralization of CRLF Sequences in HTTP Headers

Workarounds

Use with the the the non_printable_chars rule to block header injections.

ADP Enrichment

CVE Program Container

Additional References

• http://www.openwall.com/lists/oss-security/2026/05/28/9

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: yes
  • Technical Impact: partial

References

• https://metacpan.org/release/RRWO/Plack-Middleware-Security-Simple-v0.13.1/changes

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