What’s Vulnerable › Vulnerabilities

CVE-2025-40931: Apache::Session::Generate::MD5 versions through 1.94 for Perl create insecure session id

• Severity: critical (CVSS 9.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-03-05 · updated 2026-06-17
• Weakness: CWE-338

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 products

• CHORNY Apache::Session::Generate::Md5: through 1.94

References

• https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=930659
• https://github.com/chorny/Apache-Session/issues/4
• https://gitlab.ow2.org/lemonldap-ng/lemonldap-ng/-/work_items/1633
• https://metacpan.org/dist/Apache-Session/source/lib/Apache/Session/Generate/MD5.pm#L27
• https://metacpan.org/pod/Apache::Session::Generate::Random
• https://rt.cpan.org/Ticket/Display.html?id=173631
• https://salsa.debian.org/perl-team/modules/packages/libapache-session-perl/-/commit/bdabd71c2f91b18526e31a9dc52b4c17b3d246b7#898a4b8b00022df1b8689910b67707f3e738d180
• https://security.metacpan.org/docs/guides/random-data-for-security.html
• https://www.openwall.com/lists/oss-security/2019/06/15/1
• http://www.openwall.com/lists/oss-security/2026/03/05/3

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