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Vulnerabilities

Vulnerability · CVE-2025-40926

Plack::Middleware::Session::Simple versions before 0.05 for Perl generates session ids insecurely.

Published Mar 5, 2026 · catalog updated Jun 17, 2026 · Plack::Middleware::Session::Simple versions before 0.05

Check if you run it

No confirmed exploitation is on record for CVE-2025-40926. EPSS is 0.45%. Act only if a listed version of Plack::Middleware::Session::Simple versions before 0.05 is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Plack::Middleware::Session::Simple versions before 0.05).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Critical9.8
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.45%
Remediation
Advisory link
Affected products
cpe kazeburo/plack

Plack::Middleware::Session::Simple versions before 0.05 for Perl generates session ids insecurely. The default session id generator returns a SHA-1 hash seeded with the built-in rand function, the epoch time, and the PID. The PID will come from a small set of numbers, and the epoch time may be guessed, if it is not leaked from the HTTP Date header. The built-in rand function is unsuitable for cryptographic usage. Predictable session ids could allow an attacker to gain access to systems. Plack::Middleware::Session::Simple is intended to be compatible with Plack::Middleware::Session, which had a similar security issue CVE-2025-40923.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe kazeburo/plack\

How to fix CVE-2025-40926

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2025-40926. EPSS is 0.45%. Act only if a listed version of Plack::Middleware::Session::Simple versions before 0.05 is installed.

Which versions are affected?

Compare what you have installed with \. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-338; CWE-340. EPSS 0.45%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 5, 2026 · NIST NVD

    Detected

    Plack::Middleware::Session::Simple versions before 0.05 for Perl generates session ids insecurely. The default session id generator returns a SHA-1 hash seeded with the built-in rand function, the epoch time, and the PID. The PID will come from a small set of numbers, and the epoch time may be guessed, if it is not leaked from the HTTP Date header. The built-in rand function is unsuitable for cryp

  2. Jun 17, 2026 · NIST NVD

    Updated

    Plack::Middleware::Session::Simple versions before 0.05 for Perl generates session ids insecurely. The default session id generator returns a SHA-1 hash seeded with the built-in rand function, the epoch time, and the PID. The PID will come from a small set of numbers, and the epoch time may be guessed, if it is not leaked from the HTTP Date header. The built-in rand function is unsuitable for cryp

Sources

  • CVE.orgVulnerability recordCVE-2025-40926

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-40926

    30-day exploitation probability 0.4%

    first.org
  • NIST NVDVulnerability recordCVE-2025-40926

    Plack::Middleware::Session::Simple versions before 0.05 for Perl generates session ids insecurely. The default session id generator returns a SHA-1 hash seeded with the built-in rand function, the epoch time, and the PID. The PID will come from a small set of numbers, and the ep

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.