CVE-2025-59326: CryptoPro Secure Disk RCE Vulnerability

CVE-2025-59326 Overview

CVE-2025-59326 affects CPSD CryptoPro Secure Disk for Bitlocker versions prior to v7.7.4. The product fails to enforce Integrity Measurement Architecture (IMA) policy protections across temporary file systems. This gap allows unsigned code to execute from those locations, undermining the platform's code integrity guarantees.

The flaw sits at the intersection of pre-boot disk encryption tooling and Linux kernel integrity enforcement. An attacker who can stage a binary into an unprotected temporary file system can bypass IMA signature verification and run arbitrary unsigned code.

Critical Impact
Unsigned code execution on systems relying on IMA policy for code integrity, effectively neutralizing signature-based execution controls in CryptoPro Secure Disk for Bitlocker pre-boot environments.

Affected Products

CPSD CryptoPro Secure Disk for Bitlocker versions prior to v7.7.4

Discovery Timeline

2026-08-12 - CVE-2025-59326 published to the National Vulnerability Database (NVD)
2026-08-12 - Last updated in NVD database
Research disclosed at Black Hat USA in the presentation "The Cost of Obscurity" and accompanying white paper

Technical Details for CVE-2025-59326

Vulnerability Analysis

CryptoPro Secure Disk for Bitlocker provides pre-boot authentication and disk encryption workflows that rely on Linux Integrity Measurement Architecture (IMA) to validate binaries before execution. IMA appraises files against a configured policy and rejects executables that lack a valid signature.

The product's IMA policy does not cover temporary file systems mounted during operation. Because IMA appraisal is scoped by mount and path rules in policy, gaps in coverage translate directly into unenforced regions where unsigned executables can run.

An attacker who stages a binary onto one of these uncovered temporary file systems can execute unsigned code within the trusted pre-boot context. This weakens the guarantee that only vendor-signed binaries participate in the boot and authentication flow. Additional context is available through the CPSD security blog.

Root Cause

The root cause is an incomplete IMA policy configuration. Temporary file systems used by the product are not enumerated in the appraisal rules, leaving those mounts outside the enforcement boundary. IMA behaves as designed but has no rules to apply to the excluded paths.

Attack Vector

An attacker with the ability to place files into an affected temporary file system on a vulnerable host can execute unsigned binaries from that location. Because the executable never passes through an enforced appraisal rule, signature verification is skipped and execution proceeds. Exploitation details are described in the Black Hat presentation and white paper referenced above; no synthetic proof-of-concept is reproduced here.

Detection Methods for CVE-2025-59326

Indicators of Compromise

Execution of binaries from temporary file system paths (for example, tmpfs mounts) inside the CryptoPro Secure Disk for Bitlocker runtime environment
Presence of unsigned or unexpected ELF binaries staged in temporary directories used by the product
Boot-time or pre-boot audit records showing executed files that lack a corresponding IMA measurement entry

Detection Strategies

Audit the active IMA policy on hosts running CryptoPro Secure Disk for Bitlocker and identify mounts excluded from appraise rules
Correlate process execution telemetry with mount points to flag executions originating from temporary file systems
Review IMA measurement logs (/sys/kernel/security/ima/ascii_runtime_measurements) for gaps that align with temporary mount activity

Monitoring Recommendations

Forward host execution and integrity telemetry to a centralized analytics platform for retention and correlation
Alert on new executable files written to temporary file systems during pre-boot or authentication workflows
Track CryptoPro Secure Disk for Bitlocker version inventory to confirm all systems reach v7.7.4 or later

How to Mitigate CVE-2025-59326

Immediate Actions Required

Upgrade CPSD CryptoPro Secure Disk for Bitlocker to v7.7.4 or later on all affected endpoints
Inventory every host running the product and confirm patched version through configuration management
Restrict write access to temporary file systems used by the product to trusted service accounts only

Patch Information

CPSD addresses the missing IMA coverage in CryptoPro Secure Disk for Bitlocker v7.7.4. Refer to the CPSD blog and vendor release notes for exact upgrade instructions and version verification steps.

Workarounds

Where immediate patching is not possible, extend the local IMA policy to include appraise rules covering the temporary file systems used by the product
Limit local access on affected hosts to reduce the ability of an attacker to stage files into temporary mounts
Monitor and alert on executions from temporary file systems until the patched version is deployed

bash

# Configuration example: inspect active IMA policy and runtime measurements
cat /sys/kernel/security/ima/policy
cat /sys/kernel/security/ima/ascii_runtime_measurements | head
mount | grep -E 'tmpfs|ramfs'