CVE-2026-11625: Bytes::Random::Secure Perl PRNG State Sharing Across Forked Processes

Technical summary

CVE-2026-11625 affects Bytes::Random::Secure through version 0.29 and stems from improper handling of PRNG state isolation across process boundaries. The vulnerability manifests in two scenarios: (1) when a Bytes::Random::Secure object is initialized before calling fork(), and (2) when the functional interface is used without explicit per-process initialization. Because the PRNG state is shared rather than independently seeded in child processes, cryptographic material generated post-fork becomes deterministic and reproducible across the process tree. This violates the fundamental security assumption that cryptographic randomness is unpredictable. The issue is classified under CWE-335 (Insufficient Entropy), reflecting the degradation from cryptographic-grade randomness to a predictable sequence.

Business impact

Applications using Bytes::Random::Secure for cryptographic purposes in multi-process environments face severe confidentiality and integrity risks. Session tokens, API keys, encryption seeds, and other secrets become predictable to an attacker who understands the parent process state. In scenarios such as web application servers that fork worker processes, message queue consumers, or batch processing systems, an attacker could pre-compute valid credentials or encryption keys, leading to unauthorized access, data exfiltration, or system compromise. The impact extends to any downstream systems that rely on the authenticity of secrets generated by affected applications.

Affected systems

Any Perl application using Bytes::Random::Secure version 0.29 or earlier in a multi-process architecture is affected. This includes Perl web frameworks and PSGI servers that fork, parallel processing scripts, daemon processes with child workers, and background job systems. The vulnerability has no bearing on single-process applications or those that do not use Bytes::Random::Secure for cryptographic operations. Organizations should inventory their Perl dependencies and identify which systems spawn child processes.

Exploitability

Exploitability is high because no special network access, authentication, or user interaction is required. An attacker with knowledge of the parent process initialization sequence can predict the random output. The vulnerability does not require a complex exploit—understanding the timing and state of the parent process before fork is sufficient. However, practical exploitation depends on the attacker's ability to either observe or infer the parent process state, and whether the application's architecture exposes predictable secrets in a testable way. The CVSS score of 7.5 reflects the high confidentiality impact coupled with low attack complexity.

Remediation

Upgrade Bytes::Random::Secure to a patched version that properly isolates PRNG state across forked processes. Until patching is complete, mitigations include: (1) performing Bytes::Random::Secure initialization in each child process after fork() rather than before, (2) switching to alternative Perl cryptographic libraries that handle fork() safely, or (3) restructuring applications to minimize use of forked processes if feasible. Verify the vendor advisory for the minimum patch version. Any secrets generated by affected versions should be considered compromised and rotated post-patch.

Patch guidance

Check the Bytes::Random::Secure release notes and CPAN repository for version information beyond 0.29. Apply the patch in a controlled manner: test it thoroughly in a staging environment, especially in multi-process scenarios. Coordinate patching with secret rotation—old secrets generated pre-patch should be invalidated. In Perl environments managed via cpanm, ppm, or similar, dependency updates may require rebuilding downstream modules. Verify the patch by confirming that initialization occurs independently in each process and that sequential PRNG calls across forked processes produce different outputs.

Detection guidance

Monitor Perl dependency inventories for Bytes::Random::Secure versions ≤ 0.29 across your codebase and production systems. Use CPAN or dependency scanning tools (e.g., OWASP Dependency-Check with Perl support, or custom scripts querying cpanm) to identify instances. In runtime environments, check process startup logs for any fork() calls in applications known to use the library. Consider testing specific applications in a controlled lab environment: initialize Bytes::Random::Secure before forking and verify whether child processes produce identical sequences. Code review should flag any use of Bytes::Random::Secure in multi-process code paths.

Why prioritize this

This vulnerability should be prioritized as HIGH because it directly undermines cryptographic randomness in multi-process applications, a common pattern in Perl web services and batch systems. The CVSS score of 7.5 reflects high confidentiality impact with no user interaction or authentication required. Unlike vulnerabilities requiring specific conditions, this affects any multi-process Perl application using the library. The lack of complexity and high attack surface justify immediate assessment and patching of affected systems.

Risk score, explained

The CVSS 3.1 score of 7.5 (HIGH) is driven by: (1) Network-accessible attack vector—vulnerable applications are typically exposed to the network; (2) Low attack complexity—no special conditions beyond initialization; (3) No privilege requirements; (4) No user interaction; (5) High confidentiality impact—secrets become predictable; (6) No integrity or availability impact. The score correctly captures that this is a silent, high-impact weakness in randomness generation rather than a dramatic system failure.

Frequently asked questions