CVE-2026-9658Network attack vector

Header injection via ineffective CRLF path filtering

Published May 28, 2026 · Updated May 28, 2026

HTTP header injection in Robert Rothenberg Plack::Middleware::Security::Common before 0.13.1 allows remote attackers to bypass path filtering. The header_injection routine rejected double-encoded CRLF in PATH_INFO but failed to reject literal carriage-return and line-feed bytes. The rule must be enabled, and actual header injection depends on proxy and PSGI-server handling because either layer can reject or reinterpret the crafted path.

CVSS severity7.3
High
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTTP header injection in Robert Rothenberg Plack::Middleware::Security::Common before 0.13.1 allows remote attackers to bypass path filtering. The header_injection routine rejected double-encoded CRLF in PATH_INFO but failed to reject literal carriage-return and line-feed bytes. The rule must be enabled, and actual header injection depends on proxy and PSGI-server handling because either layer can reject or reinterpret the crafted path.

The record

CVE
CVE-2026-9658
Published
May 28, 2026
Updated
May 28, 2026
Vendor
Robert Rothenberg
Product
Plack::Middleware::Security::Common
Classifications
CWE-790, CWE-113, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 28, 2026CVE publishedPublication date reported by the CVE source.
  2. May 28, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <0.13.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Robert Rothenberg · Plack::Middleware::Security::Commonversion=0 <0.13.1

Published CVSS scores

7.3CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-790Improper Filtering of Special Elements
CWE-113Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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