CVE-2026-54229: ABRT D-Bus Race Condition Enables Local Privilege Escalation

Technical summary

CVE-2026-54229 is a race condition in abrt-dbus's ChownProblemDir D-Bus method. The method opens the dump directory with DD_OPEN_READONLY permissions and invokes dd_chown to reassign file ownership to the caller's UID. The vulnerability allows this ownership change to succeed even when post-create event handlers maintain active write locks on the directory. This timing window enables an unprivileged local user to gain filesystem-level control of the dump directory contents while privileged event scripts are still executing, violating intended access controls and enabling data manipulation or privilege escalation attacks.

Business impact

Organizations relying on ABRT (Automatic Bug Reporting Tool) for crash diagnostics and system monitoring face a direct threat to log integrity and system stability. An attacker could tamper with crash dumps before they're written to persistent storage or sent for analysis, obscuring system failures, masking security incidents, or triggering unintended system behavior through malicious event handler execution. On multi-user systems, this enables lateral movement from a standard user account to system-level file access. For organizations using ABRT in production environments or for compliance-required crash analysis, this vulnerability undermines the trustworthiness of diagnostic data.

Affected systems

This vulnerability affects systems running the abrt-dbus service, which is commonly included in Red Hat Enterprise Linux, Fedora, and related distributions. The vulnerability requires local access; it does not affect remote attack scenarios. Systems where untrusted local users can access the system are at higher risk. The race condition's practical exploitability depends on system load and the timing of crash event handlers, meaning high-volume crash scenarios or systems processing multiple simultaneous crashes are more exposed to exploitation.

Exploitability

Exploitation requires local system access and unprivileged user-level privileges (PR:L per CVSS vector). The attack is not trivial due to its race condition nature—an attacker must time the ownership change to occur while event handlers hold write locks, making AC:H (high complexity) appropriate. However, the attack is deterministic: an attacker can trigger crashes through application behavior or resource exhaustion, then attempt to race the ChownProblemDir call against the predictable event handler execution window. No user interaction or network access is required. Practical exploitation is feasible on systems with sufficient crash frequency or where an attacker can force crashes.

Remediation

Apply security updates from your Linux distribution vendor when available. The core remediation requires abrt-dbus to serialize ownership changes with event handler execution, ensuring DD_OPEN_READONLY cannot be held concurrently with active write operations, or to validate caller permissions before changing ownership. Until patches are available, restrict local system access to trusted users only, disable or isolate the ABRT service on systems where crash diagnostics are not required, or enforce filesystem-level access controls on crash dump directories (/var/cache/abrt or equivalent).

Patch guidance

Monitor your distribution's security advisories for patched versions of abrt. Verification should target the specific abrt-dbus package version; patch details will be announced by Red Hat, Fedora, or other affected distribution maintainers. Once patches are available, prioritize deployment on systems where local user accounts exist. Test patched versions in a non-production environment first to confirm crash reporting functionality remains intact and no regressions are introduced in event handler execution timing.

Detection guidance

Monitor for unusual permission changes on crash dump directories using auditd rules targeting chown syscalls on paths like /var/cache/abrt. Log D-Bus method calls to ChownProblemDir using DBus audit rules or application logging. On affected systems, watch for rapid sequences of crash generation followed by unexpected ownership changes, or for event handler processes (abrt-hook-* or similar) being interrupted or encountering permission errors. Review ABRT daemon logs for signs of concurrent access conflicts or unexpected method invocations from unprivileged callers.

Why prioritize this

This vulnerability merits immediate attention for systems with local multi-user access. The CVSS score of 7.0 (HIGH) reflects the combination of high confidentiality, integrity, and availability impact with local-only attack surface. While not actively exploited in the wild (KEV status negative), the race condition is technically exploitable and could be weaponized post-disclosure. Organizations should prioritize systems where ABRT is actively used for compliance or security monitoring, where untrusted local users exist, or where crash frequency is high.

Risk score, explained

The CVSS 3.1 score of 7.0 (HIGH) is justified by: (1) High impact across confidentiality, integrity, and availability—an attacker gains full filesystem control of diagnostic data; (2) Local attack vector with low privilege requirements, reducing barrier to entry; (3) High complexity due to race condition timing, which slightly dampens score but does not prevent exploitation; (4) No user interaction required, as crashes can be triggered programmatically. The absence of network accessibility and requirement for local presence prevent a critical rating, but the combination of achievable exploitation and significant system compromise justifies HIGH severity.

Frequently asked questions