--- cve: "CVE-2026-63817" severity: "HIGH" cvss: 7.8 epss: "13%" vendor: "Linux" kev: false exploited: false published: "2026-07-19 12:16:54" tags: [cve, security, high] source: tsecurity.de CVE-Dossier exported: "2026-09-17T07:55:55+02:00" --- # CVE-2026-63817 > 7.8 HIGH ## Beschreibung In the Linux kernel, the following vulnerability has been resolved: f2fs: validate compress cache inode only when enabled F2FS_COMPRESS_INO() uses NM_I(sbi)->max_nid as the synthetic inode number for the compressed page cache inode. That inode only exists when the compress_cache mount option is enabled. When compress_cache is disabled, max_nid is outside the valid inode range. A corrupted directory entry that points to ino == max_nid should therefore be rejected by f2fs_check_nid_range(). However, is_meta_ino() currently treats F2FS_COMPRESS_INO() as a meta inode unconditionally, so f2fs_iget() bypasses do_read_inode() and its nid range check, and instantiates a fake internal inode instead. Gate the compressed cache inode case on COMPRESS_CACHE, matching f2fs_init_compress_inode(). With compress_cache disabled, ino == max_nid now follows the normal inode path and is rejected as an out-of-range nid. ## CVSS-Vektor ``` CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H ``` | Metrik | Wert | Bewertung | |---|---|---| | AV Angriffsvektor | Lokal | good | | AC Komplexität | Gering | bad | | PR Privilegien | Gering | warn | | UI Interaktion | Keine | bad | | S Scope | Unverändert | good | | C Vertraulichkeit | Hoch | bad | | I Integrität | Hoch | bad | | A Verfügbarkeit | Hoch | bad | ## Patch verfügbar (OSV) - Kernel ≥ 5.15.212 - Kernel ≥ 6.1.177 - Kernel ≥ 6.6.144 - Kernel ≥ 6.12.95 - Kernel ≥ 6.18.38 - Kernel ≥ 7.1.3 ## Referenzen - - - - - - - --- _Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-63817) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_