CVE-2023-53246

cifs: fix DFS traversal oops without CONFIG_CIFS_DFS_UPCALL

MEDIUM

5.5

CVSS Score

Published: September 15, 2025 at 02:46 PM UTC

Updated: June 17, 2026 at 06:44 AM UTC

1 product affected across 1 vendorLinux Kernel

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Severity

MEDIUM5.5

Exploit prediction

EPSS 0.1%

Description

In the Linux kernel, the following vulnerability has been resolved: cifs: fix DFS traversal oops without CONFIG_CIFS_DFS_UPCALL When compiled with CONFIG_CIFS_DFS_UPCALL disabled, cifs_dfs_d_automount is NULL. cifs.ko logic for mapping CIFS_FATTR_DFS_REFERRAL attributes to S_AUTOMOUNT and corresponding dentry flags is retained regardless of CONFIG_CIFS_DFS_UPCALL, leading to a NULL pointer dereference in VFS follow_automount() when traversing a DFS referral link: BUG: kernel NULL pointer dereference, address: 0000000000000000 ... Call Trace: <TASK> __traverse_mounts+0xb5/0x220 ? cifs_revalidate_mapping+0x65/0xc0 [cifs] step_into+0x195/0x610 ? lookup_fast+0xe2/0xf0 path_lookupat+0x64/0x140 filename_lookup+0xc2/0x140 ? __create_object+0x299/0x380 ? kmem_cache_alloc+0x119/0x220 ? user_path_at_empty+0x31/0x50 user_path_at_empty+0x31/0x50 __x64_sys_chdir+0x2a/0xd0 ? exit_to_user_mode_prepare+0xca/0x100 do_syscall_64+0x42/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc This fix adds an inline cifs_dfs_d_automount() {return -EREMOTE} handler when CONFIG_CIFS_DFS_UPCALL is disabled. An alternative would be to avoid flagging S_AUTOMOUNT, etc. without CONFIG_CIFS_DFS_UPCALL. This approach was chosen as it provides more control over the error path.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Linux Kernel · Linux

95%

v < 4.14.3124.15 ≤ v < 4.19.2804.20 ≤ v < 5.4.2405.11 ≤ v < 5.15.1065.16 ≤ v < 6.1.235.5 ≤ v < 5.10.1775.7 ≤ v < 5.10.1775.7 ≤ v < 5.15.1065.7 ≤ v < 6.1.235.7 ≤ v < 6.2.105.7 ≤ v < 6.36.2 ≤ v < 6.2.1025e195aa1e607f129ab912d29fcfc792397033075.7 6.3 rc1 6.3 rc2 6.3 rc3 6.3 rc4

Vendor states this is fixed in 179a88a8558bbf42991d361595281f3e45d7edfc (fixed)

Vendor states this is fixed in 1e144b68208e98fd4602c842a7149ba5f41d87fb (fixed)

Vendor states this is fixed in 26a32a212bc540f4773cd6af8cf73e967d72569c (fixed)

Vendor states this is fixed in b64305185b76f1d5145ce594ff48f3f0e70695bd (fixed)

Vendor states this is fixed in b7d854c33ab48e55fc233699bbefe39ec9bb5c05 (fixed)

Vendor states this is fixed in 5.10.177 (unaffected)

Vendor states this is fixed in 5.15.106 (unaffected)

Vendor states this is fixed in 5.7 (unaffected)

Vendor states this is fixed in 6.1.23 (unaffected)

Vendor states this is fixed in 6.2.10 (unaffected)

Vendor states this is fixed in 6.3 (unaffected)