9.8

CVE-2025-40320: smb: client: fix potential cfid UAF in smb2_query_info_compound

Deferred
AliasesUBUNTU-CVE-2025-40320DEBIAN-CVE-2025-40320
Published 08-12-2025Last modified 15-10-2026

Vulnerability summary

CVE-2025-40320 is a critical (CVSS 9.8) vulnerability in linux. EPSS estimates a 0.42% chance of exploitation in the next 30 days, higher than 36.1% of scored vulnerabilities.

Priority
Prioritisesevere

Severe, CVSS 9.8 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 0% (FIRST, 03-11-2026)

Source freshness unavailable

How is this decided?
CVSS score
9.8/10
010
Critical · v3.1 (CVE.org)
EPSS score
0.42%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 31 · Related 28
MGASA-2026-0017MGASA-2026-0018OPENSUSE-SU-2026:20145-1RHSA-2026:18134SUSE-SU-2026:0278-1SUSE-SU-2026:0281-1

Timeline

  1. 08-12-2025
    PublishedVulnerability first disclosed.
  2. 15-10-2026
    Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix potential cfid UAF in smb2_query_info_compound When smb2_query_info_compound() retries, a previously allocated cfid may have been freed in the first attempt. Because cfid wasn't reset on replay, later cleanup could act on a stale pointer, leading to a potential use-after-free. Reinitialize cfid to NULL under the replay label. Example trace (trimmed): refcount_t: underflow; use-after-free. WARNING: CPU: 1 PID: 11224 at ../lib/refcount.c:28 refcount_warn_saturate+0x9c/0x110 [...] RIP: 0010:refcount_warn_saturate+0x9c/0x110 [...] Call Trace: <TASK> smb2_query_info_compound+0x29c/0x5c0 [cifs f90b72658819bd21c94769b6a652029a07a7172f] ? step_into+0x10d/0x690 ? __legitimize_path+0x28/0x60 smb2_queryfs+0x6a/0xf0 [cifs f90b72658819bd21c94769b6a652029a07a7172f] smb311_queryfs+0x12d/0x140 [cifs f90b72658819bd21c94769b6a652029a07a7172f] ? kmem_cache_alloc+0x18a/0x340 ? getname_flags+0x46/0x1e0 cifs_statfs+0x9f/0x2b0 [cifs f90b72658819bd21c94769b6a652029a07a7172f] statfs_by_dentry+0x67/0x90 vfs_statfs+0x16/0xd0 user_statfs+0x54/0xa0 __do_sys_statfs+0x20/0x50 do_syscall_64+0x58/0x80

CVSS metrics

5 scores · 4 sources · 2 versions

EPSS trend

Probability

0.42%

Chance of exploitation in the next 30 days

Percentile

36%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.42% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

No weakness data has been published for this record.

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Ubuntu127 products
  • linux< 6.8.0-106.106 | < 6.17.0-14.14
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-aws< 6.8.0-1050.53 | < 6.17.0-1007.7
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Debian1 product
  • linux< 6.12.63-1 | < 6.17.8-1
Linux1 product
  • linux≥ 433042a91f9373241307725b52de573933ffedbf, < 939c4e33005e2a56ea8fcedddf0da92df864bd3b | ≥ 4f1fffa2376922f3d1d506e49c0fd445b023a28e, < 327f89c21601ebb7889f8c97754b76f08ce95a0c | ≥ 4f1fffa2376922f3d1d506e49c0fd445b023a28e, < b556c278d43f4707a9073ca74d55581b4f279806 | ≥ 4f1fffa2376922f3d1d506e49c0fd445b023a28e, < 5c76f9961c170552c1d07c830b5e145475151600 | ≥ 6.6.32, < 6.6.117 | 6.8

3 vendors · 129 products

References

23 links
Show all 23 references