CVE-2026-19617: 
Vim vulnerability analysis and mitigation

CVE-2026-19617 is a Denial of Service vulnerability in libdm (the device-mapper library used by LVM2) caused by uncontrolled recursion in its configuration file parser. A local attacker can craft a malicious LVM metadata configuration with deeply nested structures, triggering stack exhaustion and crashing any LVM command that reads the metadata. The vulnerability was reported on August 12, 2026, and published to NVD and the GitHub Advisory Database on August 14, 2026. Affected products include Red Hat Enterprise Linux 6, 7, 8, 9, and 10, Red Hat OpenShift Container Platform 4, and Red Hat Hardened Images. It carries a CVSS v3.1 base score of 5.5 (Medium) per Red Hat (Red Hat CVE, GitHub Advisory).

The root cause is classified as CWE-770 (Allocation of Resources Without Limits or Throttling). The libdm-config.c configuration file parser uses recursive descent parsing with no depth limit, meaning that when it encounters deeply nested configuration structures in LVM metadata, it recurses without bound until the call stack is exhausted (Red Hat Bugzilla). Exploitation requires a local attacker to create or modify LVM metadata — for example, by placing a crafted physical volume on shared or externally-attached storage — and then causing an LVM command (e.g., pvs, vgs, lvs, vgscan) to read that metadata. User interaction is required in the sense that a privileged user or automated process must invoke an LVM command against the malicious metadata (Red Hat CVE). No public PoC exploit code has been identified at this time.

Successful exploitation results in a Denial of Service: any LVM command that reads the crafted metadata will crash due to stack exhaustion, disrupting storage management operations on the affected system. There is no impact on confidentiality or integrity — the vulnerability is limited to availability. Systems relying on LVM for storage management (including those using shared or externally-attached block devices) are most at risk, as a crash of LVM tooling could prevent volume group activation, logical volume management, or system boot processes that depend on LVM (Red Hat CVE).

No in-the-wild exploitation has been observed, and no public exploit code or PoC is known at this time. The EPSS score is approximately 0.11% (1st percentile), indicating a low probability of exploitation in the near term (GitHub Advisory). The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. The NVD SSVC assessment classifies exploitation as "none" and the attack as non-automatable (Feedly). Exploitation is constrained by the requirement for local access and the ability to write to LVM metadata or introduce a malicious physical volume.

1. Reconnaissance: Identify a target system running LVM2 on Red Hat Enterprise Linux or OpenShift where the attacker has local access or can introduce an externally-attached storage device.
2. Craft malicious LVM metadata: Create a LVM physical volume or metadata configuration file (lvm.conf or raw PV metadata) containing deeply nested configuration structures — for example, hundreds of levels of nested sections or key-value groups — that exceed the parser's implicit recursion limit.
3. Introduce the malicious metadata: Place the crafted physical volume on a block device accessible to the target system (e.g., attach a USB drive, shared SAN LUN, or NFS-backed block device with the malicious PV metadata).
4. Trigger LVM command execution: Cause the target system to scan or read the malicious metadata by running or waiting for an LVM command such as pvscan, vgscan, pvs, vgs, or lvs — which may occur automatically during system boot or udev events.
5. Achieve DoS: The libdm configuration parser recurses without limit into the nested structures, exhausting the stack and causing the LVM process to crash, disrupting storage management on the system (Red Hat CVE, Red Hat Bugzilla).

• Logs: Segmentation fault or stack overflow messages in system logs (e.g., /var/log/messages, journalctl) associated with LVM commands such as pvscan, vgscan, pvs, vgs, or lvs; kernel messages indicating process crash due to stack exhaustion.
• Process: Unexpected crashes or core dumps of LVM-related processes (lvm, pvscan, vgscan); repeated LVM command failures without an obvious configuration change.
• File System: Presence of an unfamiliar or externally-introduced block device with LVM metadata containing unusually deep nesting (inspectable via pvdisplay --maps or raw metadata dump with pvck --dump metadata).
• System Events: udev events triggering automatic pvscan on newly attached block devices from untrusted sources; system boot failures or delays related to LVM volume group activation (Red Hat CVE).

Red Hat has acknowledged the vulnerability and a patch is in progress (tracked in Bugzilla bug 2514626). Until a fixed package is released, Red Hat recommends avoiding the import of LVM physical volumes from untrusted sources without first inspecting the metadata. Systems using LVM on shared or externally-attached storage should ensure that only trusted administrators have write access to the underlying block devices. Additionally, restricting physical access to systems and controlling which block devices are automatically scanned by LVM (via lvm.conf devices/filter settings) can reduce exposure (Red Hat CVE, Red Hat Bugzilla).

Red Hat credited Tristan Madani for discovering and reporting the vulnerability. Red Hat classifies the impact as "Moderate," noting that it primarily affects systems where untrusted users have write access to LVM metadata. No significant broader media coverage or notable researcher commentary beyond the vendor advisory has been identified at this time (Red Hat CVE).