CVE-2025-5054: Canonical Apport Race Condition Vulnerability

CVE-2025-5054 Overview

CVE-2025-5054 is a race condition vulnerability in Canonical Apport up to and including version 2.32.0 that allows a local attacker to leak sensitive information via PID-reuse by leveraging namespaces. The vulnerability exists in the crash handling mechanism where the function _check_global_pid_and_forward, which detects if the crashing process resided in a container, was being called before consistency_checks, which attempts to detect if the crashing process had been replaced.

Critical Impact

A local attacker can exploit the PID-reuse race condition to forward core dumps containing sensitive memory contents to an attacker-controlled container, potentially leaking credentials, cryptographic keys, or other sensitive data from privileged processes.

Affected Products

• Canonical Apport up to and including version 2.32.0
• Ubuntu Linux 16.04 LTS, 18.04 LTS, 20.04 LTS, 22.04 LTS, 24.04 LTS
• Ubuntu Linux 24.10 and 25.04

Discovery Timeline

• May 30, 2025 - CVE-2025-5054 published to NVD
• November 3, 2025 - Last updated in NVD database

Technical Details for CVE-2025-5054

Vulnerability Analysis

This race condition vulnerability (CWE-362) affects the core dump handling mechanism in Canonical Apport, a system utility designed to collect crash reports and package them for debugging purposes. The vulnerability stems from an ordering issue in the crash handling logic that creates a Time-of-Check Time-of-Use (TOCTOU) window.

When a process crashes, Apport performs several checks to determine how to handle the core dump. The _check_global_pid_and_forward function determines whether the crashing process was running inside a container namespace, while consistency_checks verifies that the crashing process hasn't been replaced by a different process reusing the same PID.

The root cause is that these checks were performed in the wrong order—container detection occurred before the consistency verification. This sequence creates a race window where an attacker with local access can rapidly replace a crashed process with a containerized process of their choosing, causing Apport to redirect the core dump (which may contain sensitive memory contents from the original privileged process) to the attacker-controlled container.

Root Cause

The vulnerability is caused by improper function call ordering in Apport's crash handling code. The _check_global_pid_and_forward function was invoked before consistency_checks, creating a race condition window. In Linux, PIDs can be rapidly reused after a process terminates, and detecting this reuse reliably from userspace is inherently challenging. The original code did not account for this PID-reuse attack vector in the context of container namespace forwarding.

Attack Vector

This is a local attack vector requiring the attacker to have local access to the target system. The attacker must be able to:

1. Monitor for process crashes on the system
2. Quickly spawn a containerized process that reuses the PID of the crashed process
3. Have the spawned container ready to receive the forwarded core dump

The attack exploits the timing window between when a process crashes and when Apport completes its consistency checks. Due to the local nature and required race condition timing, exploitation requires specific conditions to be met. The fix addresses this by reordering function calls and adding additional safeguards—crashes are now only forwarded to containers if the kernel provides a pidfd (process file descriptor) or if the crashing process was unprivileged (dump mode == 1).

Detection Methods for CVE-2025-5054

Indicators of Compromise

• Unexpected core dump files appearing in container filesystems
• Unusual patterns of rapid process creation following crashes
• Evidence of core dumps being written to locations outside expected paths
• Suspicious process spawning activity immediately after other processes terminate

Detection Strategies

• Monitor Apport logs for unusual core dump forwarding activity to container namespaces
• Implement file integrity monitoring on core dump directories to detect unexpected writes
• Use audit rules to track apport process behavior and core dump handling events
• Deploy endpoint detection to identify rapid PID reuse patterns following process crashes

Monitoring Recommendations

• Enable detailed logging for Apport crash handling operations
• Monitor namespace transitions during crash processing events
• Implement alerting on abnormal core dump file destinations
• Review container activity logs for unexpected incoming core dumps from the host system

How to Mitigate CVE-2025-5054

Immediate Actions Required

• Update Apport to a patched version beyond 2.32.0 immediately on all affected Ubuntu systems
• Review the Ubuntu Security Notice USN-7545-1 for official patch guidance
• Audit systems for any signs of exploitation using the detection methods outlined above
• Consider temporarily disabling Apport on critical systems until patches are applied

Patch Information

Canonical has released security updates addressing this vulnerability. The fix reorders the function calls so that consistency_checks is now called before _check_global_pid_and_forward. Additionally, the patch implements stricter forwarding logic—crashes are only forwarded to containers if the kernel provides a pidfd for reliable process identification, or if the crashing process was unprivileged (dump mode == 1).

For detailed patch information, refer to the Ubuntu CVE-2025-5054 Notice and the Qualys Apport Coredump Analysis.

Workarounds

• Disable Apport crash handling temporarily by running sudo systemctl stop apport and sudo systemctl disable apport
• Restrict core dump generation using ulimit -c 0 or by setting /proc/sys/kernel/core_pattern to a safe value
• Implement strict process namespace isolation policies to limit container access to host crash data
• Use kernel-level protections like pidfd where supported to reduce PID-reuse attack surface

# Temporarily disable Apport crash handling
sudo systemctl stop apport
sudo systemctl disable apport

# Alternatively, disable core dumps system-wide
echo 0 | sudo tee /proc/sys/kernel/core_pipe_limit
echo "kernel.core_pattern=|/bin/false" | sudo tee /etc/sysctl.d/99-disable-coredump.conf
sudo sysctl -p /etc/sysctl.d/99-disable-coredump.conf