Vulnerability · Published Mar 5, 2026 · Assigned by CPANSec
CVE-2025-40931Apache::Session::Generate::MD5 versions through 1.94 for Perl create insecure session id
Critical 9.1
In plain English
A critical-severity security flaw in Apache::Session::Generate::MD5 from CHORNY. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 51% of all known vulnerabilities).
Official description
Apache::Session::Generate::MD5 versions through 1.94 for Perl create insecure session id. Apache::Session::Generate::MD5 generates session ids insecurely. The default session id generator returns a MD5 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. Predicable session ids could allow an attacker to gain access to systems. Note that the libapache-session-perl package in some Debian-based Linux distributions may be patched to use Crypt::URandom.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | libapache-session-perl | no fix listed | DEBIAN-CVE-2025-40931 |
| Debian:13 | libapache-session-perl | no fix listed | DEBIAN-CVE-2025-40931 |
| Debian:14 | libapache-session-perl | no fix listed | DEBIAN-CVE-2025-40931 |
| Ubuntu:22.04:LTS | libapache-session-perl | no fix listed | UBUNTU-CVE-2025-40931 |
| Ubuntu:24.04:LTS | libapache-session-perl | no fix listed | UBUNTU-CVE-2025-40931 |
| Ubuntu:25.10 | libapache-session-perl | no fix listed | UBUNTU-CVE-2025-40931 |
| Ubuntu:26.04:LTS | libapache-session-perl | no fix listed | UBUNTU-CVE-2025-40931 |
| Ubuntu:26.10 | libapache-session-perl | no fix listed | UBUNTU-CVE-2025-40931 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| CHORNY | Apache::Session::Generate::MD5 | 0 – through 1.94 |
Weakness: CWE-340, CWE-338 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
References
- https://metacpan.org/dist/Apache-Session/source/lib/Apache/Session/Generate/MD5.pm#L27
- https://security.metacpan.org/docs/guides/random-data-for-security.html technical-description
- https://github.com/chorny/Apache-Session/issues/4 issue-tracking
- https://rt.cpan.org/Ticket/Display.html?id=173631 issue-tracking
- https://www.openwall.com/lists/oss-security/2019/06/15/1 mailing-list
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=930659 issue-tracking
- https://salsa.debian.org/perl-team/modules/packages/libapache-session-perl/-/commit/bdabd71c2f91b18526e31a9dc52b4c17b3d246b7#898a4b8b00022df1b8689910b67707f3e738d180 patch
- https://gitlab.ow2.org/lemonldap-ng/lemonldap-ng/-/work_items/1633 issue-tracking
- https://metacpan.org/pod/Apache::Session::Generate::Random
- http://www.openwall.com/lists/oss-security/2026/03/05/3