CVE-2025-40932
Predictable Session ID Vulnerability in Apache::SessionX
Publication date: 2026-02-27
Last updated on: 2026-03-03
Assigner: CPANSec
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| grichter | apache | to 2.01 (inc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-338 | The product uses a Pseudo-Random Number Generator (PRNG) in a security context, but the PRNG's algorithm is not cryptographically strong. |
| CWE-340 | The product uses a scheme that generates numbers or identifiers that are more predictable than required. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
Apache::SessionX versions through 2.01 for Perl generate session IDs insecurely. The default session ID generator uses an MD5 hash seeded with the built-in rand() function, the epoch time, and the process ID (PID).
Because the PID comes from a small set of numbers and the epoch time can be guessed or leaked, and because the built-in rand() function is not suitable for cryptographic purposes, the resulting session IDs are predictable.
This predictability allows attackers to potentially guess or reproduce valid session IDs, which can lead to unauthorized access to systems.
How can this vulnerability impact me? :
The vulnerability can allow an attacker to predict or guess valid session IDs due to weak randomness in their generation.
If an attacker successfully guesses a session ID, they could gain unauthorized access to user sessions or systems that rely on these session IDs for authentication.
This can lead to compromised user accounts, data breaches, and unauthorized actions performed under the guise of legitimate users.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
I don't know
How can this vulnerability be detected on my network or system? Can you suggest some commands?
[{'type': 'paragraph', 'content': 'This vulnerability involves insecurely generated session IDs in Apache::SessionX versions through 2.01. Detection can focus on identifying session IDs generated by the vulnerable MD5 method, which produces predictable session IDs based on weak entropy sources.'}, {'type': 'paragraph', 'content': 'To detect this on your system or network, you can monitor session ID patterns for predictability or weak randomness. For example, check session IDs for length (default 32 hexadecimal characters) and analyze if they are generated using MD5 hashes seeded with predictable values like epoch time and process ID.'}, {'type': 'paragraph', 'content': 'Suggested commands include capturing HTTP traffic to extract session IDs and analyzing them for predictability or weak randomness. For example:'}, {'type': 'list_item', 'content': "Use tcpdump or Wireshark to capture HTTP traffic: tcpdump -i eth0 -A 'tcp port 80' | grep -i 'sessionid'"}, {'type': 'list_item', 'content': 'Extract session IDs from logs or traffic and verify if they are 32-character hexadecimal strings.'}, {'type': 'list_item', 'content': 'Use scripting (e.g., Perl or Python) to analyze session ID entropy or check for repeated or predictable values.'}] [1]
What immediate steps should I take to mitigate this vulnerability?
Immediate mitigation steps involve preventing the use of the insecure default session ID generator in Apache::SessionX versions through 2.01.
Since the vulnerability arises from using the built-in rand() function and predictable seeds (epoch time, PID), you should:
- Replace or override the default MD5 session ID generator with a more secure generator that uses a cryptographically secure random number generator.
- Ensure that session IDs are generated with high entropy sources and avoid predictable seeds like process ID or epoch time.
- If possible, upgrade to a newer version of Apache::SessionX that addresses this issue or apply patches that improve session ID generation.
- Validate session IDs rigorously to reject malformed or suspicious session IDs.