CVE-2025-15578: Maypole Perl Session ID Vulnerability

CVE-2025-15578 Overview

CVE-2025-15578 is a critical Insecure Random Number Generation vulnerability affecting Maypole versions 2.10 through 2.13 for Perl. The vulnerability exists in the session ID generation mechanism, which uses predictable seeding sources including system time (exposed via HTTP response headers), Perl's built-in rand() function, and the process ID (PID). This weak entropy combination makes session IDs predictable and susceptible to brute-force attacks or session hijacking.

Critical Impact

Attackers can predict or brute-force session identifiers, leading to complete session hijacking, unauthorized account access, and potential full application compromise without authentication.

Affected Products

• Maypole version 2.10
• Maypole version 2.11
• Maypole version 2.12
• Maypole version 2.13

Discovery Timeline

• 2026-02-16 - CVE-2025-15578 published to NVD
• 2026-02-18 - Last updated in NVD database

Technical Details for CVE-2025-15578

Vulnerability Analysis

The vulnerability stems from fundamentally flawed session ID generation in the Maypole Perl web framework. The session generation logic combines three predictable values as entropy sources: the system time, output from Perl's rand() function, and the process ID (PID).

System time is particularly problematic as it can be derived from HTTP Date response headers returned by the server. The PID is typically a small integer that can be enumerated or leaked through various side channels. Perl's rand() function, when not properly seeded with cryptographically secure entropy, produces a predictable pseudo-random sequence.

By combining knowledge of the server time and enumerating possible PID values, an attacker can significantly reduce the session ID keyspace, making brute-force attacks against session identifiers computationally feasible. Successful exploitation allows complete session takeover without requiring valid credentials.

Root Cause

The root cause is the use of cryptographically weak pseudo-random number generation (CWE-338) for security-sensitive session identifier creation. The Maypole::Session module relies on predictable entropy sources rather than cryptographically secure random number generators (CSPRNGs). The combination of time-based seeding, rand() output, and PID creates insufficient entropy for secure session tokens.

Attack Vector

The attack is network-accessible and requires no privileges or user interaction. An attacker can exploit this vulnerability through the following approach:

1. Make initial HTTP requests to the target Maypole application to obtain server timestamps from response headers
2. Enumerate possible PID values (typically ranging from 1 to 65535 on most systems)
3. Replicate the weak PRNG algorithm used by Maypole to generate candidate session IDs
4. Attempt session hijacking by submitting predicted session tokens
5. Upon successful prediction, gain unauthorized access to victim user sessions

The vulnerability can be exploited remotely without any authentication, making it particularly dangerous for internet-facing Maypole applications. Technical details of the vulnerable code can be reviewed in the MetaCPAN Module Source.

Detection Methods for CVE-2025-15578

Indicators of Compromise

• Unusual patterns of session ID submissions from single IP addresses indicating brute-force attempts
• Multiple authentication events across different user accounts originating from the same source
• Session tokens being used from unexpected geographic locations or IP addresses
• Anomalous spikes in failed session validation attempts in application logs

Detection Strategies

• Monitor web application logs for excessive session validation requests from individual sources
• Implement rate limiting on session-related endpoints to detect and prevent brute-force attacks
• Analyze session token entropy using statistical randomness tests to identify weak generation patterns
• Deploy SentinelOne Singularity to detect anomalous session hijacking behavior and lateral movement

Monitoring Recommendations

• Enable detailed logging of session creation and validation events in Maypole applications
• Configure alerts for statistical anomalies in session ID usage patterns
• Monitor for unauthorized access to user resources following suspicious session activity
• Implement session binding verification using additional factors such as user-agent and IP address correlation

How to Mitigate CVE-2025-15578

Immediate Actions Required

• Upgrade Maypole to a patched version that implements cryptographically secure session ID generation
• Replace the default session generation mechanism with a CSPRNG-based implementation
• Invalidate all existing session tokens and force re-authentication for all users
• Implement additional session validation controls such as IP binding and user-agent verification
• Consider deploying a Web Application Firewall (WAF) to detect session enumeration attempts

Patch Information

Organizations should review the MetaCPAN Module Source for details on the vulnerable code. Until an official patch is released, implementing custom session handling using Perl's Crypt::Random or similar CSPRNG modules is strongly recommended.

Workarounds

• Override the default Maypole::Session module with a custom implementation using Crypt::Random or Bytes::Random::Secure
• Implement session tokens of at least 128 bits using cryptographically secure random sources
• Add secondary session validation factors including IP address binding and fingerprinting
• Deploy network-level controls to rate-limit and monitor session-related traffic
• Consider migrating to a modern Perl web framework with secure session handling

If patching is not immediately possible, session security can be enhanced through configuration hardening. Ensure session cookies use HttpOnly, Secure, and SameSite attributes to reduce the attack surface.