CVE-2023-53137
Description
This CVE-2023-53137 has been officially rejected upstream because the original ext4-level fix it referred to (8dac5a63cf79707b...) was later reverted in Linux v6.5 (3658840cd363 ext4: Remove ext4 locking of moved directory). The upstream maintainers determined that the problem was more appropriately addressed at the VFS (Virtual Filesystem) layer, rather than within the ext4 filesystem itself. A new set of commits, starting with 28eceeda130f (fs: Lock moved directories) and followed by several refinements (66d8fc0539b0, 22e111ed6c83), implemented proper directory move locking across all filesystems. These commits are present in all maintained stable and LTS kernels, effectively rendering the ext4-specific fix obsolete. However, in older kernel branches (around v6.3–v6.4) that contain only the ext4-level patch and not the VFS-level locking changes, a narrow race condition could still theoretically occur when renaming directories, potentially leading to metadata corruption. Because triggering this race requires local access, precise timing, and provides no privilege escalation, the impact level is Low and the CVSS score should reflect low severity. In summary, while the CVE has been rejected upstream due to the alternate global fix, it can still be treated as a Low-impact condition for legacy kernels that include 8dac5a63cf79707b but lack the VFS-level locking commits (28eceeda130f and later).
Statement
Although this CVE has been officially rejected, it could be considered a low-impact security issue, as local unprivileged users might theoretically trigger filesystem corruption. However, exploitation would be highly impractical in real-world conditions. A race in ext4_rename() could let a local user who can rename directories trigger metadata corruption when the target directory changes format concurrently (inline to normal), potentially leading to filesystem corruption or crashes. The issue requires local access and precise timing (high complexity), but impacts integrity and availability of the filesystem. This issue does not provide a path for privilege escalation, but it can lead to a kernel crash and potentially result in file system corruption.
Mitigation
Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 3.6 | N/A | N/A |
| Attack Vector | Local | N/A | N/A |
| Attack Complexity | High | N/A | N/A |
| Privileges Required | Low | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | Low | N/A | N/A |
| Availability Impact | Low | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:L
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
When a race condition makes it possible to bypass a resource cleanup routine or trigger multiple initialization routines, it may lead to resource exhaustion.
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Instability
When a race condition allows multiple control flows to access a resource simultaneously, it might lead the product(s) into unexpected states, possibly resulting in a crash.
Confidentiality,Integrity
Technical Impact: Read Files or Directories; Read Application Data
When a race condition is combined with predictable resource names and loose permissions, it may be possible for an attacker to overwrite or access confidential data (CWE-59).
Access Control
Technical Impact: Execute Unauthorized Code or Commands; Gain Privileges or Assume Identity; Bypass Protection Mechanism
This can have security implications when the expected synchronization is in security-critical code, such as recording whether a user is authenticated or modifying important state information that should not be influenced by an outsider.
Frequently Asked Questions
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