CVE-2023-54177: 
Linux Kernel vulnerability analysis and mitigation

CVE-2023-54177 is a Linux kernel vulnerability in the quota subsystem, specifically a race condition that triggers a kernel warning in dqgrab() during concurrent filesystem reconfiguration operations. It affects the Linux kernel and was publicly disclosed on December 30, 2025, when it was assigned a CVE and published to NVD. The vulnerability has a CVSS v3.1 base score of 5.5 (Medium), with a local attack vector requiring low privileges (Red Hat Bugzilla, Red Hat CVE).

The root cause is a race condition (CWE-362) in the Linux kernel's disk quota subsystem (fs/quota/). The issue arises when three concurrent processes interact: one suspends quota via dquot_suspend, a second resumes quota via dquot_resume (calling dquot_load_quota_sb → add_dquot_ref), and a third opens a file with O_RDWR, triggering dquot_initialize → dqget, which increments dquot->dq_count without the DQ_ACTIVE_B flag being set. When dquot_disable subsequently calls invalidate_dquots and finds a non-zero dq_count, it calls dqgrab(), which asserts DQ_ACTIVE_B is set via WARN_ON_ONCE, triggering the kernel warning. The fix replaces the dqgrab() call in invalidate_dquots() with a direct atomic_inc(&dquot->dq_count) to avoid the incorrect assertion (Red Hat Bugzilla).

Successful triggering of this vulnerability results in a kernel WARN_ON_ONCE warning, which can cause availability impact on affected Linux systems — particularly those using disk quotas with ext4 or similar filesystems. The warning is triggered in dquot_disable+0x13b7/0x18c0 and may lead to system instability or denial of service under specific concurrent workload conditions. There is no confidentiality or integrity impact; the vulnerability is limited to availability (CVSS availability impact: High) (Red Hat CVE).

There is no known public exploit code, active in-the-wild exploitation, or threat actor attribution associated with CVE-2023-54177. The vulnerability requires local access with low privileges and a specific race condition involving concurrent fsconfig syscalls, making reliable exploitation difficult. The EPSS score is approximately 0.032% (0.000320), indicating very low probability of exploitation in the wild. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog (Red Hat CVE).

The fix is available in the upstream Linux kernel via patches committed to the stable kernel tree (commits 3f378783c47b, 6f4e543d277a, 579d814de87c, 965bad2bf1af). Users should update to a patched kernel version that includes the quota fix for dqgrab(). Red Hat has tracked this issue in Bugzilla (Bug 2426252) with severity rated as low; users of Red Hat Enterprise Linux should monitor for updated kernel packages. As a workaround, disabling disk quotas on affected filesystems would prevent the race condition from being triggered (Red Hat Bugzilla).