CVE-2025-40926

CRITICAL EPSS 34.7%
Published Mar 5, 20263mo ago · Modified Jun 17, 20262w ago
9.8 CVSS 3.1
Critical
Find Similar
Published Mar 5, 2026 3mo ago
Last Modified Jun 17, 2026 2w ago

Description

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.

CVSS Details

Base Score
9.8
Exploitability
3.9
Impact
5.9
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality High
Integrity High
Availability High

Threat Intelligence

EPSS Exploit Probability
34.7% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 2

CWE-338
CWE-340

Affected Products 1

VendorProductVersionRange
kazeburoplack\\ <0.05

References 6

  • github.com https://github.com/kazeburo/Plack-Middleware-Session-Simple/commit/760bb358b8f53e52cf415888a4ac858fd99bb24e.patch
    Patch
  • github.com https://github.com/kazeburo/Plack-Middleware-Session-Simple/pull/4
    Issue TrackingPatch
  • metacpan.org https://metacpan.org/release/KAZEBURO/Plack-Middleware-Session-Simple-0.04/source/lib/Plack/Middleware/Session/Simple.pm#L43
    Issue TrackingProduct
  • metacpan.org https://metacpan.org/release/KAZEBURO/Plack-Middleware-Session-Simple-0.05/changes
  • security.metacpan.org https://security.metacpan.org/docs/guides/random-data-for-security.html
    Third Party Advisory
  • cve.org https://www.cve.org/CVERecord?id=CVE-2025-40923
    Third Party Advisory

Remediation

  • github.com https://github.com/kazeburo/Plack-Middleware-Session-Simple/commit/760bb358b8f53e52cf415888a4ac858fd99bb24e.patch
    Patch
  • github.com https://github.com/kazeburo/Plack-Middleware-Session-Simple/pull/4
    Issue TrackingPatch