Description

openssl_encrypt 1.4.x before 1.4.9 contains an optional D-Bus crypto service whose org.freedesktop.DBus.Properties.Set method performs neither a polkit authorization check nor value validation. Any local user on the system bus can call Set without authorization and set MaxConcurrentOperations (to 0/negative, causing the concurrency gate to refuse all subsequent operations, or to a huge value removing the limit) or the unbounded DefaultTimeout, resulting in a persistent denial of service of the root daemon. The D-Bus service exists only on the 1.4.x line and was removed in 1.5.x.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.2",
  "pubDate": "2026-08-27T17:20:58.257Z",
  "pubdate": "2026-08-27T17:20:58.257Z",
  "executiveSummary": "A critical security vulnerability exists within the D-Bus crypto service integrated into openssl_encrypt versions 1.4.x prior to 1.4.9. The vulnerability is characterized by a complete absence of polkit authorization checks and input validation in the org.freedesktop.DBus.Properties.Set method.\nThis flaw allows any local user with access to the system bus to interact with the service and arbitrarily modify internal configuration parameters. By injecting malicious values into parameters such as MaxConcurrentOperations or DefaultTimeout, a local attacker can induce a persistent denial of service (DoS) affecting the root-privileged daemon.\nThe risk is significant due to the nature of the service, which operates with elevated privileges. Successful exploitation results in the complete cessation of crypto operations managed by the daemon, effectively disabling core cryptographic functions for the system. This vulnerability is specific to the 1.4.x branch and is not present in version 1.5.x.",
  "technicalDetails": "The vulnerability resides in the D-Bus interface of the openssl_encrypt daemon, specifically within the handling of the org.freedesktop.DBus.Properties.Set method. The root cause is the failure to implement mandatory Access Control Lists (ACLs) or polkit authorization checks when processing property change requests. Furthermore, the daemon fails to perform bounds checking or type validation on the input provided to the method, trusting the D-Bus message payload implicitly.\nThe attack flow begins with a local attacker identifying the exported D-Bus service on the system bus. The attacker then constructs a malicious D-Bus message directed at the org.freedesktop.DBus.Properties.Set method, targeting specific properties of the openssl_encrypt service. Because the interface lacks authorization gating, the daemon processes the request regardless of the caller's privilege level.\nBy manipulating the MaxConcurrentOperations property, an attacker can set the value to 0 or a negative integer. This triggers the service's internal concurrency gate to reject all subsequent cryptographic operations, effectively locking the daemon into a non-functional state. Conversely, setting this property to an excessively large value can lead to resource exhaustion or unexpected state transitions.\nSimilarly, the DefaultTimeout property is susceptible to modification. By setting this to an unbounded or extreme value, an attacker can manipulate the operational lifecycle of ongoing crypto tasks, inducing service instability or persistent timeouts that degrade system performance and reliability.\nThe scope of impact is local, requiring the attacker to have an existing foothold on the host system to interact with the system bus. Since the targeted service runs with root privileges, the consequences of this exploitation are systemic. The vulnerability is persistent, meaning the altered state remains until the daemon process is restarted or the properties are manually reverted, if possible. The vulnerability is constrained to the openssl_encrypt 1.4.x series and was effectively mitigated by the removal of the vulnerable D-Bus service in the 1.5.x release branch."
}