CVE-2026-98005

Overview

The Linux kernel's erofs filesystem used an ambiguous inode_share cache key that combined a fingerprint and domain ID without a separator. This could allow the fingerprint to be interpreted as part of the domain ID, producing incorrect in-memory cache key indices. It matters because ambiguous cache keys can undermine filesystem integrity and may expose or corrupt shared inode metadata.

Description

In the Linux kernel, the following vulnerability has been resolved: erofs: delimit inode_share cache key components Previously, inode_share keys were encoded as follows: fingerprint || domain_id It would be better to have a separator between the fingerprint and domain ID so that the fingerprint won't be parsed as part of a domain ID. Change the key encoding as follows: domain_id || '\0' || fingerprint Since domain_id is a NUL-terminated string, this makes the in-memory key indices unambiguous.

Impact

Confidentiality and integrity may be affected if an attacker can influence erofs image contents or mount parameters, causing cache key ambiguity. Availability is less likely but could be affected by incorrect inode sharing behavior. Local users or processes able to prepare or mount erofs images are the primary impacted group. Remote impact is not indicated by the description.

Remediation

Apply vendor kernel updates that include the erofs inode_share cache key fix. If patching is delayed, restrict creation and mounting of untrusted erofs images and limit mount privileges to trusted administrators. Audit systems for custom or third-party erofs images and remove or quarantine untrusted ones. Monitor kernel logs for filesystem anomalies after updates.

Risk context

CVSS v3 5.5 places this in the medium range, and no EPSS score is provided. Treat as a routine kernel patching item, prioritized higher for systems that mount untrusted erofs images or run in multi-tenant/local-privilege contexts.

Affected products

• Linux kernel
• Linux kernel erofs filesystem