CVE-2026-43154

Vulnerability

CVE-2026-43154 is a vulnerability in the Linux kernel's EROFS file system. The bug occurs in the volume label handling code, where crafted EROFS images containing valid volume labels can cause the kernel to execute incorrect early returns. These early exits lead to a failure in properly releasing folio references, resulting in a folio reference leak. The root cause is a logic error in the control flow when processing volume labels from a maliciously crafted filesystem image.

Exploitation

To exploit this vulnerability, an attacker needs to be able to mount a specially crafted EROFS image on a target system. This could be achieved through local access (e.g., by a user mounting a malicious filesystem) or potentially via a remote vector if a system automatically processes EROFS images from untrusted sources. The attack does not require authentication beyond the ability to mount a filesystem. The vulnerability is triggered during the mount operation when the kernel reads and processes the volume label from the image.

Impact

Successful exploitation results in a folio reference leak, which can lead to gradual memory depletion over time. However, according to the official description, this vulnerability does not cause system crashes or other severe issues. The impact is limited to memory leaks, which could degrade system performance if triggered repeatedly. The CVSS v3 base score is 5.5 (Medium), reflecting the availability impact due to resource exhaustion.

Mitigation

Patches for this vulnerability have been committed to the Linux kernel stable tree. Affected users should update their kernel to versions containing the fix. The specific commits are referenced in the kernel's stable repository [1][2][3]. No workaround is provided, as the fix involves correcting the logic in the volume label handling code.