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CVE-2026-9658

HIGHCVSS 7.3/10EPSS 0.23%

Last modified

CVE-2026-9658 is a high-severity vulnerability rated 7.3/10 on the CVSS scale. 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.. EPSS estimates a 0.23% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
7.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

EPSS Probability
0.23%

13.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

References

Timeline

Published
Last Modified
Status
Deferred

Frequently Asked Questions

What is CVE-2026-9658?
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.
How severe is CVE-2026-9658?
CVE-2026-9658 has a CVSS score of 7.3/10 (HIGH severity). The EPSS model estimates a 0.23% probability of exploitation in the next 30 days.
How do I fix CVE-2026-9658?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-9658?

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Source: NVD / NIST