CVE-2026-41564
Published: 23 April 2026
Summary
CVE-2026-41564 is a high-severity PRNG (CWE-335) vulnerability in Dcit Cryptx. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Credential Access (T1212); ranked at the 2.9th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 RA-5 (Vulnerability Monitoring and Scanning) and SI-2 (Flaw Remediation).
Deeper analysis
CVE-2026-41564 is a vulnerability in CryptX versions before 0.088 for Perl, where the Crypt::PK modules—including RSA, DSA, DH, ECC, Ed25519, and X25519—fail to reseed their per-object PRNG state after forking. These modules initialize a PRNG state in their constructors and reuse it without fork detection, causing any Crypt::PK object created before a fork() call to share byte-identical PRNG state with all child processes. This results in identical outputs for randomized operations, such as key generation, across processes and maps to CWEs-335 (Incorrect Generation of Random Numbers) and CWE-338 (Use of Cryptographically Weak or Nonce-Repeating PRNG).
The vulnerability particularly affects preforking services like the Starman web server, where a Crypt::PK object loaded at startup is inherited by every worker process. Remote attackers with network access and no privileges (AV:N/AC:L/PR:N) can exploit this by collecting two ECDSA or DSA signatures from different processes, enabling nonce-reuse attacks to recover the signing private key. The CVSS 3.1 score of 7.5 reflects high confidentiality impact (C:H) with no integrity or availability disruption (S:U/I:N/A:N).
Advisories recommend upgrading to CryptX 0.088, available on MetaCPAN, which addresses the issue. A fixing patch is provided at https://github.com/DCIT/perl-CryptX/commit/9a1dd3e0c27d68e32450be5538b864c2b115ee15.patch, and further details appear in the GitHub Security Advisory GHSA-24c2-gp6c-24c6 and an oss-security mailing list post at http://www.openwall.com/lists/oss-security/2026/04/23/2.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-25201
Vulnerability details
CryptX versions before 0.088 for Perl do not reseed the Crypt::PK PRNG state after forking. The Crypt::PK::RSA, Crypt::PK::DSA, Crypt::PK::DH, Crypt::PK::ECC, Crypt::PK::Ed25519 and Crypt::PK::X25519 modules seed a per-object PRNG state in their constructors and reuse it without fork detection. A Crypt::PK::*…
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object created before `fork()` shares byte-identical PRNG state with every child process, and any randomized operation they perform can produce identical output, including key generation. Two ECDSA or DSA signatures from different processes are enough to recover the signing private key through nonce-reuse key recovery. This affects preforking services such as the Starman web server, where a Crypt::PK::* object loaded at startup is inherited by every worker process.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
The vulnerability enables remote exploitation of public-facing preforking services to recover private keys via nonce-reuse attacks on ECDSA/DSA signatures, directly mapping to exploitation for credential access.
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Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly mandates timely remediation of flaws such as the CryptX PRNG reseeding failure after forking by applying patches or upgrades.
Requires vulnerability scanning to identify deployments of vulnerable CryptX versions before 0.088, enabling proactive patching.
Enforces secure cryptographic key generation and management practices, mitigating weak PRNG outputs like nonce reuse in forked processes.