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CVE-2026-63817— f2fs: validate compress cache inode only when enabled

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel 5.14版本存在安全漏洞，该漏洞源于禁用compress_cache时，F2FS_COMPRESS_INO()将max_nid视为元索引节点，导致f2fs_iget()绕过nid范围检查并实例化虚假内部索引节点。

CVSS 7.8 · High EPSS 0.13% · P3

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 6ce19aff0b8cd386860855185c6cd79337fc4d2b< fcc051d377a9701a452e7663a1a8223c26225df9 affected
6ce19aff0b8cd386860855185c6cd79337fc4d2b< 29115b8c9172d34e67ab26cc4f6c209b7a236d7a affected
6ce19aff0b8cd386860855185c6cd79337fc4d2b< 13e4b59d3a9413f66f116fa6c4828519b960a5ea affected
6ce19aff0b8cd386860855185c6cd79337fc4d2b< 16161444c30d8dff9428abbae42b72ce4e32a932 affected
6ce19aff0b8cd386860855185c6cd79337fc4d2b< 77f216ff9ce5cde8eed9f6d12707e906dffdc9f7 affected
6ce19aff0b8cd386860855185c6cd79337fc4d2b< 0969926d987bbde9a1aa49da317582ba37095805 affected
6ce19aff0b8cd386860855185c6cd79337fc4d2b< 5073c66a96a9c23c0c2533ed4ed06e42f9021208 affected
a23706426da9b611be5beae0f3faa260fb453b4e affected
… +10 more rows
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I. Basic Information for CVE-2026-63817

Vulnerability Information
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Vulnerability Title
f2fs: validate compress cache inode only when enabled
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel 5.14版本存在安全漏洞，该漏洞源于禁用compress_cache时，F2FS_COMPRESS_INO()将max_nid视为元索引节点，导致f2fs_iget()绕过nid范围检查并实例化虚假内部索引节点。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 6ce19aff0b8cd386860855185c6cd79337fc4d2b ~ fcc051d377a9701a452e7663a1a8223c26225df9 -
Linux Linux 5.14 -

II. Public POCs for CVE-2026-63817

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III. Intelligence Information for CVE-2026-63817

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Patches & Fixes for CVE-2026-63817 (7)

Same Patch Batch · Linux · 2026-07-19 · 429 CVEs total

CVE-2026-63795 10.0 CRITICAL 9p: avoid putting oldfid in p9_client_walk() error path
CVE-2026-64091 9.8 CRITICAL batman-adv: tt: fix TOCTOU race for reported vlans
CVE-2026-63984 9.8 CRITICAL ipv6: rpl: fix hdrlen overflow in ipv6_rpl_srh_decompress()
CVE-2026-64025 9.8 CRITICAL bpf, skmsg: fix verdict sk_data_ready racing with ktls rx
CVE-2026-63922 9.8 CRITICAL ipv6: exthdrs: refresh nh after handling HAO option
CVE-2026-63979 9.8 CRITICAL net/handshake: hand off the pinned file reference to accept_doit
CVE-2026-64056 9.8 CRITICAL net: ethernet: cortina: Make RX SKB per-port
CVE-2026-63800 9.8 CRITICAL pNFS: Fix use-after-free in pnfs_update_layout()
CVE-2026-63978 9.8 CRITICAL net/handshake: Drain pending requests at net namespace exit
CVE-2026-64055 9.8 CRITICAL net: ethernet: cortina: Carry over frag counter
CVE-2026-63808 9.8 CRITICAL exfat: fix potential use-after-free in exfat_find_dir_entry()
CVE-2026-64033 9.8 CRITICAL RDMA/rtrs: Fix use-after-free in path file creation cleanup
CVE-2026-63888 9.8 CRITICAL scsi: target: iscsi: Fix CRC overread and double-free in iscsit_handle_text_cmd()
CVE-2026-63887 9.8 CRITICAL scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf
CVE-2026-64113 9.8 CRITICAL ixgbevf: fix use-after-free in VEPA multicast source pruning
CVE-2026-63825 9.8 CRITICAL gcov: use atomic counter updates to fix concurrent access crashes
CVE-2026-63857 9.8 CRITICAL net: airoha: Do not read uninitialized fragment address in airoha_dev_xmit()
CVE-2026-64160 9.8 CRITICAL netfs: Fix potential for tearing in ->remote_i_size and ->zero_point
CVE-2026-64125 9.8 CRITICAL net: bcmgenet: keep RBUF EEE/PM disabled
CVE-2026-63924 9.8 CRITICAL ipv6: exthdrs: refresh nh pointer after ipv6_hop_jumbo()

Showing top 20 of 429 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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