EUVD-2026-20060
GHSA-gr8m-rq4x-q7c8
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Lifecycle Timeline
3Description
Amon2::Plugin::Web::CSRFDefender versions from 7.00 through 7.03 for Perl generate an insecure session id. The generate_session_id function will attempt to read bytes from the /dev/urandom device, but if that is unavailable then it generates bytes using SHA-1 hash seeded with the built-in rand() function, the PID, and the high resolution epoch time. 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. Amon2::Plugin::Web::CSRFDefender versions before 7.00 were part of Amon2, which was vulnerable to insecure session ids due to CVE-2025-15604. Note that the author has deprecated this module.
Analysis
Amon2::Plugin::Web::CSRFDefender versions 7.00 through 7.03 for Perl generate cryptographically weak session IDs when /dev/urandom is unavailable, falling back to SHA-1 hashing seeded with predictable values (system PID, epoch time, and the unseeded rand() function). This allows attackers to forge valid session identifiers and potentially conduct session hijacking or CSRF attacks. …
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External POC / Exploit Code
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