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Fencer Intel
high 7.3

CVE-2026-9658 json

Plack::Middleware::Security::Common versions before 0.13.1 for Perl did not block header injections in request paths

published 5mo ago modified 16d ago also EUVD-2026-32892

cvss
7.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 13%
public exploits
0
none known

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.

Patch / fix

  • RRWO Plack::Middleware::Security::Common 0.13.1

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CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
5mo ago

Exploit prediction

0.23% chance of exploitation in the next 30 days, higher than 13% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
CNA 3.1 7.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Affected products

  • RRWO Plack::Middleware::Security::Common

Classification

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

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.