CVE-2025-40926Plack::Middleware::Session::Simple versions before 0.05 for Perl generates session ids insecurely
- 9.8CriticalCVSS base score
- 0.50%Exploitation in 30 daysEPSS · top 56% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By CPANSec
- 11 months later
· 11 months later
Published
- 47 days later
· 47 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| CISA-ADPADP (enrichment) | 3.1 | Critical9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Modified | 3.1 | Critical9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.50% · top 56% of all CVEs (13 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.8.
Affected products
KAZEBURO · Plack::Middleware::Session::Simple
- affected < 0.05
What to do
Solution: Users are advised to upgrade to version 0.05 or later.
Workaround: Users are advised to change the sid_generator attribute of Plack::Middleware::Session::Simple to a function that returns a securely generated session id based on a secure source of entropy from the system. Users may consider using Plack::Middleware::Session version 0.35 or later.
References
References6
- https://metacpan.org/release/KAZEBURO/Plack-Middleware-Session-Simple-0.04/source/lib/Plack/Middleware/Session/Simple.pm#L43 (opens in a new tab)
- https://github.com/kazeburo/Plack-Middleware-Session-Simple/pull/4 (opens in a new tab)issue-tracking
- https://github.com/kazeburo/Plack-Middleware-Session-Simple/commit/760bb358b8f53e52cf415888a4ac858fd99bb24e.patch (opens in a new tab)patch
- https://www.cve.org/CVERecord?id=CVE-2025-40923 (opens in a new tab)vendor-advisoryrelatedvdb-entry
- https://security.metacpan.org/docs/guides/random-data-for-security.html (opens in a new tab)technical-description
- https://metacpan.org/release/KAZEBURO/Plack-Middleware-Session-Simple-0.05/changes (opens in a new tab)release-notes
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2025-208296 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2025-40926)Record last updated .