CVE-2026-9638: Crypt::PBKDF2 versions before 0.261630 for Perl generate insecure random values for salts

Synopsis

An insecure random number generation vulnerability affects Crypt::PBKDF2 for Perl in versions before 0.261630. The library uses Perl's built-in rand function to generate password-hashing salts, which is predictable and not suitable for cryptographic use. Exploiting this weakness over the network requires no authentication and allows an attacker to recover plaintext passwords from hashed values. A patched-image rebuild at version 0.261630 is available on HarborGuard for environments running an affected version.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityRequired

  The attacker must be able to reach the service over the network; any internet-exposed or internally networked service using this library is in scope.

• AuthenticationNot required

  No account or credential is needed to exploit the weakness; the attack targets the predictability of salts produced by the library, not a protected endpoint.

• Victim interactionNot required

  No user action is required; exploitation is passive and relies entirely on the attacker's ability to observe or obtain hashed password values.

• Attack complexityDetail

  The exploit is reliable and condition-free once hashed values are obtained, as salt predictability from rand is a deterministic property of the library with no environmental dependencies.

Blast Radius

• An attacker who obtains hashed password values can reconstruct the salts used during hashing and accelerate brute-force or dictionary attacks to recover plaintext passwords.
• Recovered plaintext passwords expose user credentials stored or processed by any application relying on Crypt::PBKDF2 for password hashing.
• Confidentiality of all password material protected by this library is fully compromised; integrity and availability of the host system are not directly affected by this vulnerability.