CVE-2023-53246: cifs: fix DFS traversal oops without CONFIG_CIFS_DFS_UPCALL
Vulnerability summary
CVE-2023-53246 is a medium (CVSS 5.5) NULL Pointer Dereference vulnerability in linux. EPSS estimates a 0.15% chance of exploitation in the next 30 days, higher than 4% of scored vulnerabilities.
Not severe (CVSS 5.5, local access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 6 · Related 5Timeline
- 15-09-2025PublishedVulnerability first disclosed.
- 11-05-2026Last modifiedVulnerability information updated.
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.
CVSS metrics
4 scores · 3 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.15%
Chance of exploitation in the next 30 days
Percentile
4%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.15% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu124 products
- linuxAll versions (No fix recorded) | < 5.4.0-156.173 | < 5.15.0-79.86
- linux-allwinner-5.19All versions (No fix recorded)
- linux-awsAll versions (No fix recorded) | < 5.4.0-1107.115 | < 5.15.0-1042.47
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Linux2 products
- linux≥ 25e195aa1e607f129ab912d29fcfc79239703307, < 26a32a212bc540f4773cd6af8cf73e967d72569c | ≥ 25e195aa1e607f129ab912d29fcfc79239703307, < b64305185b76f1d5145ce594ff48f3f0e70695bd | ≥ 25e195aa1e607f129ab912d29fcfc79239703307, < b7d854c33ab48e55fc233699bbefe39ec9bb5c05 | ≥ 25e195aa1e607f129ab912d29fcfc79239703307, < 1e144b68208e98fd4602c842a7149ba5f41d87fb | ≥ 25e195aa1e607f129ab912d29fcfc79239703307, < 179a88a8558bbf42991d361595281f3e45d7edfc | 5.7
- linux_kernel< 4.14.312 | ≥ 4.15, < 4.19.280 | ≥ 4.20, < 5.4.240 | ≥ 5.5, < 5.10.177 | ≥ 5.11, < 5.15.106 | ≥ 5.16, < 6.1.23 | ≥ 6.2, < 6.2.10 | 6.3:rc1 | 6.3:rc2 | 6.3:rc3 | 6.3:rc4
Debian1 product
- linux< 6.1.25-1
3 vendors · 127 products
